> Short answer: more fun.
> 
> Long answer: there aren't a lot of female character I really like/admire and just generally its more fun to go as a male character, for me anyway. Plus most of these ideas are based on things I already own/easy to find. I'd love to be Chell or Sam Carter or even Eowyn but I don't have the time/money to make those costumes and I don't want a half-assed costume. I'd rather focus on somethig simpler that I can do really well. 

I understand now. Plus I imagine there's a bit more pressure in general for "girl" costumes.

I would recommend Spiderman or Jedi.

I don't think those first two on your list are recognizable enough. And I bet there are going to be soooooooooo many half-assed Doctors. If you do the Doctor you gotta go all out.