I was considering asking for some private lessons in Venusian Aikido, but I actually don't think the Doctor would be a very good instructor. Not enough patience for explaining the fundamentals.So Tony, what are your choices?
I'd probably stick to the modern age. I think the level of technical and pedagogical knowledge in unarmed martial arts is higher than it's ever been. (Knowledge of sword arts has probably dropped off drastically over the last couple of centuries, but I'm less concerned about archaic weaponry.)
Lots of great choices for BJJ. I'd probably go with Ryron Gracie for teaching ability, technical skill, attitude, and a good fit with my personal BJJ goals.
For Judo I might go with Neil Adams. I'm sure there are other Judo coaches just as good or better, but he's the best I've encountered personally and I've wished I had more opportunities to learn from him.
My third choice it would probably be either Marc Denny for DBMA or Rodney King* for boxing.
*(The South African Rodney King, not the guy who got beat up by the LAPD.)