Hard to say...
As weapons go, i´ll always be a sword man, so, Leo on that.
As character go, all have something to offer, but i´ll go with Ralph on this one
All in all, Ralph wins it
The cool thing is, the four of them represent the teenage years.
Michelangelo is the immature, crazy, party teen, always happy with being alive
Raphael is the melancholy, trying to find a place where to fit in, which makes in violent and a rebel, an outcast
Leonardo is always worrying too much about everyone, always wanting for things to go smoothly, always trying to be a father figure
Donatello is the unknown, the discovery
Basically...
Michelangelo = Spider-Man
Raphael = Wolverine
Leonardo = Cyclops
Donatello = Reed Richards