For me, I think I'd pick either Nolan Batman (because then I don't have to deal with supernatural crap and I could retire if I wanted to without having to worry about Darkseid conquering the Earth or something) or maybe DCAU Batman because its not quite as bad as some of the other continuities, and hey, Justice League.
For Nolan Batman...
Honestly, I'm not sure Gotham is broken enough that it needs a vigilante. We see some corrupt officials at high levels, but is it really any worse than some real-world cities? Even if the local government is broken, I can probably use Wayne Enterprises to push for more Federal intervention, and back more honest politicians at the state and local level (though I might try to scupper Dent's campaign, given that I know he has tendencies towards mental instability).
I can also pour money into charitable organizations to offer a higher standard of psychiatric care than Arkham, and to alleviate poverty in Gotham, and so on.
The problem is that Ras is already on a collision course with Gotham at this point, and will target me. But once I take down Ras, I can probably safely quit the vigilante game. I'll also make every effort to take Ras alive. Hopefully that'll keep Talia from going full nut job. Maybe, if I get to them early enough, Talia and Bane can be rehabilitated. Hell, both could become valued Wayne Enterprises employees if I don't kill Talia's father and they get some therapy.
I basically need to do three things to sink Ras:
1. Have a trap set for him when he infiltrates Wayne Manor (say, twenty Wayne Enterprises private security guys).
2. Locate the stolen microwave weapon.
3. Find some way to draw the cops' attention to Crane sooner, and get to work on an antidote to his chemicals sooner.
Granted, there's a risk that Ras might expose me as a vigilante if taken alive, but I have a few options there. Convince him that with him taken down, I'm the only hope to restore balance. Find something to blackmail him with. Last resort: use Crane's toxin on him, which should reduce him to a mental state that will cause his testimony, if he's even capable of delivering any, to lack credibility.
Plus, if he does finger me, I have plenty of Wayne Enterprises money and lawyers at my disposal.
If the Joker's rampage still happens (its implied that he was one of those Ras let out of Arkham in Batman Begins, I believe), then I hope that the reforms I've implemented among Gotham's law enforcement and government, and the assistance Wayne Enterprises can offer them, will be enough to allow the cops to capture him.
Then I guess maybe I propose to Rachel and settle down. Will make Alfred happy too. Or maybe Talia, if reformed.
After that...
Well, I'll be a wealthy, politically-influential philanthropist if I play my cards right. If Nolan-verse politics follows real-world politics... well, I wonder what the results of Bruce Wayne endorsing Bernie Sanders for President would be?
DCAU is a different deal- superhero vigilantes are common and mostly accepted by society, and their are threats that require counters beyond what mundane methods can deal with. But by the same token, I'm not sure Batman is as necessary in a world with Superman. Of course, the counter-argument is that Superman and so on won't focus on Gotham specifically, and can't be everywhere at once.
And of course, the JL lacks accountability (see Waller's position). But I'm not sure what, if anything, the lesser evil to the JL is.
Still, I can employ much the same methods as above. Leverage my wealth and knowledge into scientific research, charity work, and political influence. Be the financier and logistical support for the Justice League, more than a front-line fighter (though I wonder if the JL would respect the input of someone who didn't fight on the front line).
Of course, at the start of my career the JL doesn't exist yet. So helping to piece it together early might be a good move.
Oh, and try not to end up a lonely old man like canon DCAU Bruce.
"I know its easy to be defeatist here because nothing has seemingly reigned Trump in so far. But I will say this: every asshole succeeds until finally, they don't. Again, 18 months before he resigned, Nixon had a sky-high approval rating of 67%. Harvey Weinstein was winning Oscars until one day, he definitely wasn't."-John Oliver
"The greatest enemy of a good plan is the dream of a perfect plan."-General Von Clauswitz, describing my opinion of Bernie or Busters and third partiers in a nutshell.
I SUPPORT A NATIONAL GENERAL STRIKE TO REMOVE TRUMP FROM OFFICE.