I have so many that I like and I've learned to fight well with. I'll just list my top ten:
1.) Janemba
2.) SSJ Vegetto
3.) SSJ Goku
3.) SSJ4 Vegeta
4.) Vegetto
5.) SSJ Goten
6.) Kid Buu
7.) Evil Buu
8.) Piccolo
9.) Final Form Frieza
10.) Perfect Cell
I know it's a long list, but that's only a few of the people I like to use.
I'm a big DBZ fan. Some of my favorite characters are Vegeta, Cell, Janemba and definately Trunks. I am a moderator for the Budokai Tenkaichi forums.