Batman Beyond. I grew up with it as being my defining version of Batman. I love the show, Terry, the villains, the stuff that could be done with the fantasy future tech, the whole shebang. But the fact this is one of the most depressing endings for Bruce Wayne EVER put into media makes me feel like any interactions I would have with other DC character, Batfam especially and no matter what universe they were from, would always be tainted by Terry having this knowledge that "Oh yeah, BTW I come from a universe where Batman grew old, became bitter and alone, and successfully drove away every single person he ever cared about." It's like having a permanent pall cast over everything that can't really be gotten rid of since Terry's arc is tied so closely to being Bruce's successor.