What's the best Genesis (and Game Boy Color) emulator?

[James]

I finally decided to get off my ass and download some of my old Genesis games for ease. I tried Xega, but it would just crash every time I tried to open it. So I've been using Gens, but it could be a bit better.

I don't see a lot of options (the two mentioned, and one for DOS), so I was just wondering if you guys knew of any others that you were happy with.

Also, any recommendations on an emulator that plays both Game Boy and Game Boy Color games? Or at least an emulator for each?