I'd prefer a younger , fresh Batman to fully distinguish from the older Batman of TDKR and the Nolanverse. We've seen a middle aged Batman , its time to go back to a younger version for the reboot imo. I'd also like to see supporting characters which haven't been used or exploited much like Leslie Thompkins as a mother figuare to Bruce , which has been lacking in these films , and maybe a Female Cop who helps Batman much like in TBM animated series in this film.
As far as a villan goes , I think it really depends on which direction they wanna go. I'd like to see them go the whole Detective / crime syndicate/ Mystery/ Noir route. In that case, I'd love to see Black Mask and Reaper. Yeah, they did reaper in MOTP , but its been nearly 20 years, and I highely doubt the GA knows who the Phantasm even is , or has seen the film. Plus its a good character and you wouldn't have to have it be Andrea Beaumount as it was in BTAS. I'd have it be the same character from the original story. Plus it opens opprunities to use Joe Chill in a way he's never been used before.
This would be my dream cast
Bruce Wayne/ Batman: Sam Witwer
Alfred Pennyworth : Geoffrey Rush
Leslie Thompkins: Helen Mirren
Reaper : David Morse
Joe Chill:Robert Carlyle
Black Mask : James Frain
Detective Ellen Yin: Maggie Q