If you don't want to do 20's, then may as well go to 29 as already mentioned. Get the extra abilities, Glyph slot and chance at better gear from dungeons etc, also Freezing Trap at 28. Go the whole hog and twink it out at 29.
I'd say all 3 hunter specs would be good at 29. They all get Counter Shot and Multi-Shot. BM gets the extra Beast Cleave, probably better for PvE rather than PvP, but it is useful in flag fights.
My advice, go 29 and choose which ever Hunter spec you prefer, all will top the DPS charts