I'd just like to say that any of the 3 specs are viable, you just know what the heck your doing, and its not always about dps.
A SV hunter can be out dps'd sure, but properly geared it can give other raid members massive dps (bout 270ap with mine buffed up)at all times.

A bm hunter, if smart, will keep pet alive and keep the 3% extra dmg buff up for group when pet critically strikes, in a long fight 3% is alot.

A MM hunter can throw out big hits and big dps.TSA and silencing shot are awesome.

I have personally raided with all 3 specs, each spec has its own talents and can provide for a group many different ways, so there is no best spec.

Yes I know I missed a lot of stuff but this is just an example.
(and 5 am so Idc for full detail)

Ok, I have been reading this thread and some posts just make me want to throw up.  Some people just cant be more wrong.  When it comes to raid dps, BM is superior with the pet added in.  And no, it is not hard at all to keep the pet alive since blizzard implemented avoidance.  Not only is BM better dps, but it is also more mana efficient, will a better group buff than MM.  The only thing I hate about being BM is having to refill my quiver all the time :/
And, also, BM is superior to marksmen and survival when it comes to duels and 2v2s.

I know many people aren't going to agree with me, but marksmanship is the way to go for 5v5s.  Improved stings, silencing shot, aimed shot(which most BM hunters will probably have too), scatter shot and improved concussive shot are all priceless when it comes to those 5v5s.  On top of that, you get great burst dps, which is obviously better for pvp than consistent dps.

Survival hunters are worse at dps than BM, and worse than MM at pvp, BUT one is a must-have in 25 man raids.  Expose weakness is one of the best raid buffs there is, especially if that survival hunter is stacked with agility. Not to mention there are a few good pvp talents in there as well.  And about the CC buffs in Survival, I think they are a waste of points.  Any hunter who knows how to trap well does not need to spend points into their traps in order to do it.  I have 0 points in that tree and still keep someone trapped the entire moroes fight and hex lord fight.  Not only that, but what use are traps in 25 mans?  Don't waste your points, spend them in dps.

just to have credibility:
http://www.wowarmory.com/character-sheet.xml?r=Ravencrest&n=Birdsong

http://i255.photobucket.com/albums/hh134/Shoinzo/AB.jpg
http://i255.photobucket.com/albums/hh134/Shoinzo/battlegroundpwnage.jpg

true, but us SV/MM hybrids crit like crazy.

ex.

crit
hit
hit
crit
crit
dead

regular mob anyway

I just went mm/sv 20/41 and i crit crazy. I'm also crittin for 2.5k which makes me happy lol. happy I switched to it.