My personal favorite for flawed reasons is Madoka because I was there for the live reactions to the infamous episode and it was magical watching everyone lose their shit. It was also my re-introduction to anime after being shamed out of it for liking sailor moon as a kid.
That all sounds dope as hell. Would you rec one over the the other to start with? Madoka was one of my first anime so it kinda spoiled me, but on the plus side I’ll always enjoy a new show by gen.