David Tennant said just recently that he used Patrick Troughton's portrayal of the Doctor to base his own and believed every actor since Troughton has done the same.
Pertwee was his own Doctor, definitely not based on Troughton. Baker, hmm, no not really Troughton.
Davison, definitely see Troughton there.
Colin Baker seems to have drawn more from Hartnell.
McCoy, hmm, a bit of Troughton.
Don't remember enough about McGann to know.
Eccleston really didn't draw much on any previous Doctor.
So, I don't totally agree with that. But Davison, Tennant, and Smith, yes can see that they drew on Troughton.