I don't know if the OP is still watching this thread anymore but I thought I'd share my thoughts, bear in mind though I haven't been playing in the 29 bracket that long and currently only have a 29 Rogue in it (am working on more however), so take what I say with a pinch of salt.
'Best' is a very vague term really, it depends on what you want to get out of the 29 bracket. I'll try and break it down a bit as best I can:
Healing - Currently I think it is safe to say that Priests and Paladins are the healing heavyweights of the bracket. Without going into the details of each of the classes spells, both fill this roll very well if spec'd correctly. Shaman and Druids do alright but I feel they are currently more of a support class than a straight healer. Bear in mind that in patch 3.2 Druids will be getting Travelform at level 16, and I predict a wave of resto druids incomming.
Flag Carrying - Many classes can actually fill this role very well if geared/ spec'd correctly. However I would say the top contenders are:
Druids are a good choice with their speed increase in catform (feral spec'd), travelform in 3.2 will be nice too, ability to instantly root attackin melee and can ofcourse shift out of snares.
Good Shaman annoy the crap out of me when I'm in def, if I haven't killed them by the time they are out of the base I'm pretty much done for. They have instant ghostwolf (spec'd properly), ability to remove poisons (crippling) and lots of snares in the form of frostshock, frostbrand weapon & earthbind.
Paladins have good mitagation, good 'oshit' buttons and ofcourse Hand of Freedom, need I say more.
DPS/ HK's / KB's/ etc - If all you want from the 29 bracket is to have a low(ish) death count, high damage and alot of killing blows then roll a Hunter. Be warned however that there are alot of hunters in BG's nowerdays so if you want do better than average then you are going to have to twink better than average. Hunters do have limited utility but mainly bring damage to the table, if you are going to take the time to master the class I can't see you being beaten very often in 1v1.
Rogues are also high up on the Damage, HK and KB charts. If you manage to find a BG with only a few hunters in it then your Deaths will probably be low too. Rogues bring a little more utility to the table than hunters, able to slow down EFC's more effectively than Hunters giving your team more time to close in, decent flag carriers and so on. Also as far as you fighting hunters is concerned, as a rogue if I am caught out of steath by a pretty decent hunter twink who is at distance then in all probability I am going to die, however if I manage to get the first shot in then I will win the vast majority of times even against well twinked well played hunters, it's their ability to keep you at distance which screws us over the most.
After these two main DPS classes the others all tend to do pretty well too if spec'd and geared correctly of course:
- Balance druids are not bad, however Feral ones don't cut it from my experience.
- Mages can put out some nice damage and can be quite slippery for melee classes, however in a time where hunter twinks make up the majority of 29 bg's, if you role a mage .. expect to die alot.
- Ret paladins are a strong class with great burst, good ones can give me alot of trouble if I don't focus.
- All priests now have devouring plague DOT along with their old friend SW
ain, if a priest can survive long enough these dots alone can normally kill many classes.
- Warlocks I personally find quite squishy in general and easy to lock down .. but then again I'm an undead rogue so it's kind of a no brainer. However they are able to put out ALOT of damage and I've often died after fights with good warlock twinks just due to the damn dots still ticking away.
- Finally Warriors and Shaman, I haven't seen any or atleast noticed any DPS twinks of these classes so unfortunately I cannot comment on their effectiveness, however I assume both are pretty good too.
Overall, if you don't really know what role you want to go into pick a class you like at 80, check out what talents and spell are availiable to it at 29 and if it seems interesting give it a go. 29 is a good bracket where most classes stand a chance against one another.