In no particular order
Nightcrawler in ANYTHING because I find him sad-cute and his powers are just bad-ass.
Gambit from the 90s cartoon because I like his accent and his personality!
Rogue from the 90s cartoon for the same reason as Gambit, and because she just generally angsted less than the other versions.
Beast from the 90s cartoon because he could quote Shakespeare and Newton WHILE kicking ass. I found it hilarious.
Lower on my list are Cyclops, Shadowcat, Mystique, and sometimes Archangel.