I'm one story, Survival, away from completing a rewatch of classic Who, and I would be another to like a Troughton vibe, though Matt Smith did try for a bit of that. His try seemed to me more about mannerisms because for me what Troughton did well is almost act from the side of things. He didn't take centre stage so much. It's difficult to see if someone else could do that because I am not sure how you would know. I guess what I am wanting is a good Iago and that's hard to see in most people. Of the people in the list provided TV, I would probably lean to Jo Martin.
I quite like Steve's suggestion of Meera Syal. I think linking in with the good Iago, you want a not quite lead actor, that can drip with intelligence. I would suggest Mark Bonnar but that maybe too many Scots.