Well, Patrick Stewart and Anthony Head would be my first picks, but I don't think they're even an option (although Stewart should at least make a guest appearance already).
Rolling different ideas through my head, here are some actors I'd like to see take up the Sonic Screwdriver:
- Philip Glenister
- Ben Daniels
- Samuel West
- Tobias Menzies (the Doctor with an edge? Menzies' very good playing sinister)
So, looking at the actors I came up with, I guess I'd like to see a more mature Doctor again.