Beat 'em Ups is one of those genres that I've always liked, but never gotten heavily into. Growing up in the arcade era, I played the usual famous ones. The Simpsons, Teenage Mutant Ninja Turtles: Turtles in Time, Die Hard Arcade, X-Men... uhh I'm sure there were more but those are the only ones that come to mind. I also remember Battletoads, Double Dragon, Gekido, the Fighting Force series and Splatterhouse 3 for the consoles.
When I got into emulation, the Streets of Rage series, Alien Storm, Golden Axe series and Altered Beast were acquired and played. Again, probably missing something, but those were the standout ones.
Finally, the ones I've enjoyed as an adult and old man. Streets of Rage Remake, Streets of Rage 4, Dungeons & Dragons: Chronicles of Mystara, Dynamite Cop, Final Fight, Scott Pilgrim, Dragon's Crown and last but certainly not least is Armored Warriors.
I just need to get a tiny bit of bitching about Scott Pilgrim off my chest. Great game all around, but the way you gain stats sucks. I think it would have been better if each character had their own stats instead, like in Streets of Rage. It is what it is though, didn't stop me from beating it a few times.
In conclusion, a great genre and I'm glad there's plenty of classics and new indie games to keep things going.