I'm just a bit young to have seen Pertwee as a child. Eccleston is a really strong actor, I think, with a surprising range considering how distinctive his voice & ears are.

Tennant was intermittently ok, and I've enjoyed some of his other stuff. I think he was terribly written & badly directed, and the whole thing played more and more to a small section of the audience. I lost interest entirely before the end of Tennant, so I've never seen Smith in the part, but he's far far too young.