Oddly both options are good, I had a hunter at 63 when the nerf hit, and leveling went way faster. Though this was my first time to 70 and the nerf had hit part way through I think outlands leveling is much less painful than old world.

On the othert hand I did purpostly leveled healers with my RAF to help out the flood of DK's coming through.

So like I said both are good.