Most Helpful Guy
I always say with this stuff, you have to go with your instincts. Nobody here can tell you for sure what any of these guy's true intentions are. But just going by what you've said - I think you probably know "guy A" is someone you're more into for an actual relationship than he is with you. Probably best to consider him a potential "friends with benefits" if that's an arrangement you're comfortable with.
Personally, I think way too many women screw up by passing up the "sweet" guys who may or may not have the "sexiest" bodies (but are at least somewhat "cute"). A nice personality can last a lifetime, but looks fade (and can change quite a bit before that, sometimes for the better). So if "guy B" seems interested in more than just being friends, I think you should take that opportunity - vs. investing more energy on "guy A".
Most Helpful Girl
I think guy B sounds like a better choice.