A bit more context: My friend feels he doesn't have the reaction speed for first person shooters, hasn't played many of them (other than some of Metroid Prime back when it was still fairly new), and has nearly no experience with Keyboard and Mouse, usually sticking to games that allow for using a controller.

In a way, it's not just a question of which class is good for someone new to Borderlands itself, but also which class would be good for someone new to first person shooters in general. I only have experience with two classes myself (Zer0 and Maya), so I don't feel that comfortable making the decision for him.

That said, if I'm trying to make the experience as painless for him as possible, which class and skill tree(s) would likely be the best bet for someone with very little first person shooter experience?