I like trying to use the characters that don't get used, and also the ones who I just love as characters. Thusly Olimar turning out to be my main man. Playing friend matches I haven't seen anybody use olimar more than one match, and in random brawls I've yet to see olimar at all. And I don't know why, he's a beast. He's a bit strange, but he's super quick, and has incredibly long range smash attacks. His only weakness is being so damn light.
Triple D is popular as a character (because he's a freakin penguin/boxer/self proclaimed king with a giant mechanized mallet!!) but I still don't see a whole lot of people use him, because of the difficulty of using him. In a free for all he can destroy, but 1 on 1 it takes ALOT of finesse to not get raped against anybody that's halfway decent.
I haven't been able to get into Wario yet, even though he's in my sig and I really want to use him. He's cool, fluid, his moves are fast and combine well, but he can be kind of akward with his skill set, and he just hasn't gotten the same attention from me that Olimar and D3 have.
Link is my old stanby, my main since the original, and I usually only use him if I want to do some rapage old school. I pwn hard with Link, but i try to use the newer less used characters when possible.
You can find me on facebook as Markus Van Rijn, if you friend me just mention you're from VGchartz and who you are here.