Soul Calibur series
Yoshimitsu. I like quirky tricksters with good mix-ups. Add the fact he's a bit looney, goofy, yet an awesome looking ninja(though he dresses like a samurai) and I'm there. I thank Sc2 for getting me to love this cool character.
Whatever Street Fighter game(Alphas, USSFIV, etc)
Sakura Kasugano for whatever Street Fighter game. While Ryu and Dan are fun, I ought to spend time getting her right. When I first saw her, I became attracted to main a genderbend of Ryu. Only thing was her personality was tomboyish. I particularly like hard working yet spunky tomboyish girls such as Asuka Kazama and Seong Mi-na. That aside, I'm interested in improving with her.
DOA5U
Kokoro, Momiji, and Zack. Zack for lulz, Momiji because I ought to try out this lovely lady, Kokoro because that's who I want to main: a lovely ba-ji maiko that can fight.
Tekken series
Yoshimitsu and Asuka Kazama. See Street Fighter and Soul Calibur opinions.
Everything else I didn't mention
I dabble around until I find mains that click with me. Then, all I need is some competition and I'm there.