My list:
1) Colin Baker (as discussed)
2) Tom Baker (ditto)
3) Paul McGann (instantly clicked for me--we wuz robbed. After Tenant, they really ought to go back to the eighth Doctor. Yeah, it's been 12 years or so, but he was wearing a wig anyway; they could pull it off, and besides, who knows how long he lasted in that incarnation?)
4) Christopher Eccleston (maybe not #4 in terms of the character, but raised up by the quality of the acting)
5) Patrick Troughton (fun, well done)
6) David Tenant (good job, just a bit...er, something)
7) Jon Pertwee (classic, but somehow not quite "there"...also hard to describe)
8) Peter Davison (yeah, a little bland, but what killed it for me was Tegan, who was in almost all his episodes, bleah!)
9) William Hartnel (and yeah, a fuddy duddy, but sometimes that was good

)
10) Sylvester McCoy (I didn't care for his acting much, and a lot of his stories were awful)