I find that there are certain characteristics my PCs all share in common, and I cannot get away from them; my characters are just about always lawful in some way or other; they act as if a strong, centralized authority acting for the good of the populace is the best alternative to whatever currently exists. My PCs may lead a revolt to overthrow a tyranny, but never want to replace it with anarchy.
My characters are always gonna try to help the weak/downtrodden. I've tried to modify this, but it doesn't work; give me an orphanage to defend, and there I am, whether I'm a spoiled rotten halfling mafia-princess, or a half-elf wandering bard who likes to dance topless...
And I'm almost always the face for any party I'm in. I guess because I'm most interested in the "story", I can't stand hours of "shall we/shan't we" behavior. I dive in and give advice, make decisions and talk to people. Even my dwarf fighter who never really "talks" to people is inclined to move things along (he grabs his axe and starts smashing something, live, dead or breakable).
So my characters are all ME; they just have different "clothing". I wish this were less true than it is...