I try and avoid having more that one person with the same innate color except for annoying boss battles. But I'm always switching characters around because they are all so magnificent. The only character I avoid is Poshul, she just annoys me, plus Leena and Mojo are a lot cooler than her.

My favorite characters to use are Serge (The swallow is a really cool weapon), Harle (she is just so amazing) NeoFilo (use leech seed type attack!), Guile (magic wand of awesome), Kid/Mel/Fargo (klepto time) and Riddel (restoring elements is a big +)