My top 3 without a doubt:
1. Christopher Eccleston
2. Tom Baker
3. Jon Pertwee
Tennant: too hyper, talks too fast, couldn't understand him 1/3 of the time.
Troughton: Seemed too unsure of himself for a timelord.
Smith: Too bombastic? Still think he's odd looking.
Davidson: Indifferent to him. Compared to Pertwee, a bit of a wuss.
Colin Baker: Annoying
McGann: YES! Liked his voice. He'd be #4 on my list.
Sylvester McCoy: I liked how he had some mystery to his character which they unfortunately never fully explored.
Hartnell: No, back to the drawing board.
Tennant: I love that about him personally, that's what made him a great doctor. He was fun.
Troughton: I liked him, I still think he might be the funniest doctor to date, especially when you compared him to Pertwee in the three doctors. Maybe he was a bit too unsure, but remember he was still quite a bit younger back then.
Smith: I'm give or take on him. I like the fact he looks strange, all part of that alien look.
Davison: Same here. I felt I've never seen him at his best though, his only really good story in my mind I've seen is Earthshock. I wouldn't really call the five doctors or the dalek one one of his greatest stories though.
C. Baker: I only found his outfit annoying. But I think he was quite a good doctor. Could be annoying at times though.
McGann: One of my faves too (my second to be precise). Just wish we saw him more.
McCoy: Totally agree. I have a feeling he would have stayed on for five series if it was not cancelled, and by then we'd have fully explored him a bit more. Would have probably been in the role for the second longest.