I'd just pick the most popular one, which is likely to have the most software, drivers, polish, online answers... So, Ubuntu. (Well, after Android, technically, but that's not really applicable).
I had dual boot for a while, but I just ended up using only one of them. I think that's a common problem with dual boots. (O.t.o.h., if you use Windows for games and Linux for coding, you can keep work and spare time separated).