Not Cumberbatch (though I actually think he could play it very differently to how he plays Sherlock, but he’s too well known now) and not Elba (love him to bits but don’t think he’s Doctor material). I haven’t seen enough of Ben Daniels to make a judgement, though I do at least know who he is now!
Alexander Siddig. I think he’d be fantastic, he manages to be quintessentially English whilst also embracing his heritage. At 47 he might be a shade too old, but (despite what Garak said) he still retains his boyish charm, and it would be nice to see a suave Doctor again, certainly he’d be very different from 9, 10 and 11, which is ideally what we need. He’s a good enough actor to play the light and dark of the character, and I could see him being both playful and manipulative, plus I think it’d be funny if the Doctor had a beard rather than the Master this time
Paterson Joseph. For the same reason EMH picked Eddie Izzard, nostalgia for a man who could have made a great Doctor in the mid-nineties…if the show had still been running.
Bradley James. Yup not Merlin, Arthur! Actually he’d be more my pick for the 13th Doctor rather than the 12th because I think he needs to be older, but I think he could be a very good, Davison style Doctor.
Ian Glenn. Would be amazing, but sadly he’s probably too old (though saying that he isn’t that much older than Siddig or Ben Daniels.
Robert Glenister. That’s right, not Gene Hunt, Gene Hunt’s brother, because frankly he’s a far better actor than his brother. Again probably too old now, but it would be funny if Salateen from Androzani turned up decades later as the Doctor…
I like Adrian Lester, but actually I think he’d make a better Master, and the other name that always crops up is Chiwetel Ejiofor, who I’m kinda conflicted over. I’ve seen him in some very good roles, but I’ve also seen him in some bland roles. He is a good actor, and well known, without being so well known/so good that he’s going to fly off to Hollywood after a few years.
If they go with a woman
Nicola Walker has always been my preferred choice, plays the part of a scatty old lady in a young body to a tee in Spooks (especially her early seasons.) but I’d now lean towards Olivia Colman. Feted by BAFTA just a few weeks ago with awards for both her comedy and drama roles she’s a fine, multi-talented actress who could be scatty and wacky one minute, but have you firmly believing she’s going to throw you out of an airlock (without a suit) the next
Of course in all likelihood the next Doctor will be someone I’ve never heard of