I concur. Pokemon professor would definitely be my choice.
However, my second choice is Pokemon. Sure, we may get beat up a lot, but we don't have to worry about money and other boring stuff like that. Plus, if we're owned by a trainer, then we get free food! How cool is that? We'd get to make friends with other pokemon that the trainer owns. The best part, though, is that we get awesome super powers. Imagine being able to fly, or to shoot high-pressure water or flames from your mouth. Being able to generate earthquakes at will and manipulating the elements. If I were a Flygon like I always dream of being, then I would be able to fly anywhere I like. If things get rough, then I can fly away. However, most pokemon would be too intimidated by me to even try picking a fight.
Never played any of the Ranger games, so I have no idea what being a ranger would be like. It's probably not as awesome as being a pokemon, though.