Yeah, Bill is pretty solid. Bill and Gary's Excellent Adventure sold me on him. I like pretty much all the characters. Vidae said it a while ago, but all their abilities are interesting and have drawbacks.
Plus a lot of the characters themselves are just interesting. I think we've already established my love for how awesome Gary is.
Nina's my favorite character, I don't even care if it's being forced down our throats, Nina & Rozen are both truly awesome. Besides looks, I like that these two clearly have a deeper history in the 'Alpha' program, she is not just some newbie and is probably the most experienced of the core team.
Can't fault anyone for loving Gary though, clearly a badass.