I've loved the progression from Doctor to Doctor.

Eccleston's Doctor was a step away from PTSD. His absolute rage at the beginning is tempered by Rose by the end of the series.

Then Tennant's Doctor was a bit more a part of the world. And he felt better than the world. He was selfish and hypocritical and on more than one occasion, gets called out on it.

So then Smith's Doctor was intentionally more child-like and whimsical. He's the funny old doctor. And at the same time, he seems much OLDER than the previous two. Like a guy in a retirement home trying to prove to the kids he's still hip and doesn't really want them off his lawn...the fact that he's physically younger just accentuates that.

I like them all, both in individual series and when looking at it as a whole. Fun stuff.