A tale of two character transformations

I watched both "THE GODFATHER" and "THE GODFATHER, PART II" on DVD in the space of a few nights.
I'll weigh in on the great debate about which film is better: I actually prefer the first film. I prefer the original, I think, because of the character of MICHAEL CORLEONE (AL PACINO).
The first film features an arc of character development unseen in the sequel -- at least in Michael. Michael begins that first film as an outsider, wary of the criminal activities and the dangerous brutality of his family. By the end, his character has hardened into the very thing he despised.
At the beginning, though, Michael is very much a sympathetic character.
That isn't the case in the sequel, where Michael's brutality flows throughout the film.
One could argue that the character of young VITO CORLEONE (ROBERT DE NIRO) makes a similar progression, from good to evil, on the streets of early 20th Century New York. However, I view Vito's transformation as one of adapting for survival in a somewhat lawless, alien community. I don't see his character's metamorphosis in the same light as Michael's transformation in the original.
Here I go, thinking too hard about movies again. Hey, it could be worse: I could be agonizing over the two consecutive games of COMPUTER HEARTS I've just lost. Lost badly. Dang it.