As you know I started my new Shadowpriest as a proud member of the Troll race. I thought it might be interesting to go over each of the races a Shadowpriest can play and look at the various racials that may affect your choice.
With the exception of Draenei, I would say that the Alliance racials are more useful for the PvP side of World of Warcraft. You can currently choose to play any of the Alliance races apart from Gnomes. Lets be honest, you wouldn't really want a Gnome Shadowpriest anyway.
Arguably the best PvP racial at this moment in time, Every Man for Himself means that you will not need to have a PvP Trinket to break out of any movement impairing effects (Polymorph, Fear, Hammer of Justice etc). This means that not only can you use this skill whenever you may need it but also you do not need to waste a Trinket slot on the PvP Trinket in PvP situations. This will allow you to pick another trinket that you would not usually be able to equip.
Perception is another great PvP racial, it is now a passive ability. This means that you will constantly have improved stealth detection and have a much better chance of spotting those sneaky rogues / feral druids before they strike. The passive ability equates to 5 stealth detection at all times and that means you will see any stealthed player as if you were 1 level higher than them. This may sound odd but if you imagine looking at a lower level rogue whilst they are stealthed, they are easier to spot.
The Human Spirit racial is a 3% buff to your total spirit. This is a nice bonus to your shadowpriest but not a game changer. The racial used to be considerably higher and offered a 10% increase to your spirit, however this was considered to high and was later nerfed. Yes thats right, Blizzard nerfed the human spirit :< href="http://www.wowhead.com/?spell=20599">increase to their reputation gains which is always going to be useful. Any human player will receive 10% additional reputation from quests, killing mobs or playing in battlegrounds. Whilst this racial is not going to improve your end-game DPS or make you a better PvPer, it makes life a little easier and is a welcome addition.
All in all, I personally think the Human Shadowpriest is the single best for any kind of Player vs Player situation when looking solely at racial abilities. It also provides a great range of different racials that any kind of player will enjoy. If you are looking for the best PvP combination then the Human Shadowpriest is for you. Alternatively if you are looking for a race that will provide advantages in all types of your gameplay then you can't go wrong with a Human.
Dwarf Shadowpriests have the ability to use Stoneform allowing them to remove all poisons, diseases and bleeding effects from themselves. Shadowpriests can already remove diseases from themselves but being able to get rid of any bleeding and poisons instantly is pretty damn useful. However this does have a 2 minute cooldown and therefore must be used at the right time. Although I would say this ability is mainly aimed at PvP it does have some uses in PvE to remove a raid wide poison effect from yourself and save your healer the trouble. I'm sure you guys and girls can think of times when a racial like this could have saved you and your repair bill.
However apart from Stoneform, Dwarf Shadowpriests don't have much joy with racial abilities. Sure they have a pretty nifty Frost Resistance that you will probably never really notice and finding treasure is great if it wasn't so useless in Northrend. Personally I would never pick a dwarf on racials alone and I really hope they get some love in Cataclysm.
Night Elves would be considered fairly weak in terms of racials if it wasn't for Shadowmeld. Not only does that racial begin with the word 'Shadow' it is also incredibly useful to all types of players. This ability instantly stealthes the player and takes them out of combat, although you cannot move whilst stealthed this simple ability offers several important advantages.
You can use it in PvE to leave combat and stay stealthed directly before a raid wipe and then pop out of shadowmeld and ressurect the raid when the boss / raid trash has reset position. This will not only make other players happy but it will keep your repair bill nice and low. If you manage to attract the attention of an enemy NPC then you can use Shadowmeld to reset your threat and return the attention of the NPC to the tank. In some situation in both PvE and PvP you will be able to use Shadowmeld to leave combat and then drink to replenish your mana. When attemptign this please remember that you will break the stealth once you begin drinking and so you will need to attempt this at the right time and place. Shadowmeld has some other great uses like avoiding an enemy spellcast or avoiding enemy players in battleground / World PvP but I won't go into detail about these.
Other than Shadowmeld, the Night Elf racials offer very little to a Shadowpriest. Faster travel in ghost form and Nature Resistance are not going to change your gameplay. Quickness may be considered useful in PvP if you combine it with other factors but once again its not really going to be the difference between Gladiator and Challenger.
I would say that Draenei players have the "best" racial ability for a PvE Shadowpriest. Heroic Presence increases your chance to hit with spells by 1%. Unless you have raided as a DPS class before then you will probably be thinking that sounds useless. I will quickly explain how this works:
For every player the spell hit cap is 17%. This means if you have 17% hit then you will not miss any current raid boss or mob with your spells. Shadowpriests usually pick the talents Misery and Shadow Focus, which means that they now only need 11% hit. If you are a Draenei Shadowpriest you will only need 10% hit to reach the 'hit cap' where you will no longer miss the target you are fighting. It is almost always considered correct to reach the hit cap through your gear stats and then you can think about other stats you may want on your gear. This 1% hit offered by the racial simply means that you can reach the hit cap easier and then focus on more stats that will increase your DPS.
Draenei players also receive a Shadow Resistance racial that when coupled with your Shadow Resistance buff, may actually be considered pretty great in PvP. Finally Gift of the Naaru is an instant cast HoT that heals the player for 1235 health over 15 seconds. However as far as I am aware it does actually break Shadowform even though it is a racial, therefore it is only useful when you intend to lose Shadowform to heal yourself. It is a nice little extra HoT but it would be a hell of a lot more useful to us if it didn't drop our lovely Shadowform.
The Horde currently only have three options for rolling a Priest, but the racials they offer are pretty interesting.
Will of the Forsaken has always been debated when looking at PvP and the different racial abilities that can be used. It has recently taken a nerf and shares a separate 45 second cooldown with the PvP Trinket. A lot of people are upset by this change and think this reduces the benefit of the racial considerably. For a shadowpriest I still think its great in any PvP scenario. In my opinion, if you use the right timing and put a little thought into when and what you use your PvP Trinket/WOTF with then it can still be an exceptional racial. This is without mentioning that Priests already have the option to use Fear Ward and the right player in the right situation can mitigate a whole chain of Crowd Control. Getting nerfed blows, but you need to think about how to adapt to these nerfs to really improve your gameplay in my opinion.
I think that Cannibalize is a very underrated racial as it allows Shadowpriests to heal themselves without breaking Shadowform which is such an advantage in certain situations. Also nothing says "I win" like eating the corpse of your opponent. Pretty much a PvP / soloing racial but still a great little ability that looks awesome. Shadow Resistance when combined with your own Shadow Protection is always a bonus and Underwater Breathing is well...better than nothing.
Undead Shadowpriests make a really great PvP choice for their racials but are lacking in the PvE department.
Players that pick Troll Shadowpriests receive some really great racials. Most importantly the Beserking ability that increases casting speed by 20% every 3 minutes. This is a great ability in itself and is only made better by the fact that the recent haste changes mean that Shadowpriests now receive some great benefits from stacking haste. In my opinion this is the best PvE racial available to a Shadowpriest at the moment. It is more difficult to state how useful it is in PvP because you are always adapting to your opponent. However this ability will allow you to increase your burst damage or throw some really quick heals depending on the situation. Definitely a great racial for whatever your playstyle.
Passive abilities such as Beast Slaying and Da Voodoo Shuffle are actually incredibly useful to Shadowpriests and help make the Troll a great choice for both PvE and PvP content. I picked a troll for my own shadowpriest and I am very pleased with the racial abilities he offers.
The Blood Elf has two racials worth having a look at. First off is Arcane Torrent which silences all nearby enemies and provides 6% of your base mana. The mana regen may be pretty useful when soloing or leveling but is not really going to be that useful in PvE where most Shadowpriests don't have any real mana issues if they have their rotation and gear planned out carefully. Where this racial ability really shines is within PvP, this ability is off the GCD (Global Cooldown) and the two second silence can work wonders. Combine this ability with the Shadowpriest spell Silence and you are looking at some serious PvP benefits.
The other racial you might want to take a look at is Arcane Resistance which similar to the other racials of its type may offer certain advantages in PvP.
The Blood Elf Shadowpriest can be great in PvP when looking at the racials alone, but simialr to the Undead it holds no real advantage in a PvE scenario.
In conclusion to this post, I want to mention something very important. The information I have provided is purely looking at racial abilities and how they can be useful. However WoW characters are not just a set of numbers on a DPS meter or just an Arena Rating, they represent yourself in the game and therefore try not to pick your character because someone told you to. Racial abilities are great but they are not going to make or break the game for you, so never be afraid to pick a class / race combination that isn't considered the "best". Pick your race because you like it.
I picked my troll because he dances like a pro.