Quote:
Mobs 2/3 levels below you to minimize downtime and maximize exp/hour gain. Gathering and kill quests mixed with this is a great combination.
For any other class I would agree, for hunter though, I found mobs even level to 1 level higher to be the most efficient to grind on. I was BM spec though and my pet could basically solo a same level mob.
I would highly suggest BM spec for leveling if you aren't already and try to find an area with lots of caster mobs.
For level 48 head to
Feralas
Felwood
Burning Steppes/Searing Gorge