BoS would be my pick. That is, i am asumming you went prot to tank at your level. If you picked it thinking it is the fastest way of leveling up, you will be missing some key talents... including BoS and reckoning.
Reckoning gives you couple more hits, but BoS gives you extra threat and damage to all targets hitting you. Seems to me, that if you are tanking at your level you will need the extra threat from BoS, combined with Right. Fury and ret aura.
In the end though, it doesnt really matter, since you will probably pick BoS and reckoning (although since 2.3 different builds have emerged). Your levels will go by fast, so don't worry too much about it.