Dick has the full package of skills, but I’m not sure he could handle being tied down to Gotham. He’d be a good Batman, but I’m not sure being Batman would be good for him.
Jason’s entire point is that he doesn’t like the way Batman does things. Terrible choice.
Tim doesn’t want to be Batman and he’s not quite the fighter Bruce is. He does have the detective skills and strategic ability, but I see him doing his own thing or quitting the hero game entirely.
Damian would love nothing better than to be Batman, but he doesn’t get the mission at all.
Barbara, being entirely redundant with Dick ever since Flashpoint, would be a solid successor for all the same reasons he is, and admittedly maybe slightly more comfortable in the role since her new personality is fine being tied down to the Bat.
Cass understands the reasons Bruce does what he does better than just about any of the others (except maybe Dick, but I’d say that while he might understand, Bruce’s motivations, he doesn’t exactly share them; he operates more out of a sense of camaraderie and responsibility as opposed to having the nigh-pathological drive to save lives that Bruce and Cass do). She’s also the best at all the ninja stuff. The only issue is the detective skills and higher-level strategy. She’s far from stupid, but she can’t read and tends to bring any evidence she gathers to other people to actually make sense of it.
Stephanie’s probably a poor choice. She’s a decent all-rounder, but there are better choices by any metric.
Batwoman is another one like Jason or Damian who I don’t think quite “gets” it, so while she could probably do the actual job pretty well, I don’t think she’d be as effective as Dick or Barbara.
While Knightfall is not quite a fair representation of what Jean-Paul Valley would do as Batman because that was before he resolved a lot of the Issues with his brainwashing… he still has way too many issues. And yes, it’s really weird saying that someone has too many issues to be Batman, but Azrael manages to pull it off.
Luke Fox could be a decent choice. He’s a bit of a showboater, but he’s smart and has an appropriate sense of theatrics. The only issue is that I almost feel like he doesn’t have enough issues to be as driven as Batman.
Terry McGinnis obviously worked out pretty well in practice, so it depends on when this transition takes place. If Bats kicked the bucket right now, Terry is probably still like three years old. But in the future? Sure.
So, if we assume one new Bat (no teamups), here’s my ranking:
I still stand by my earlier choice of a Cass-and-Tim dynamic duo, though. Maybe Cass as Batwoman and Tim as a new Oracle.