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.
Kind of a lame answer:Undertale. But not for the nonviolence thing, which had already been done before. I'm talking about the whole concept of the no mercy route, with Flowey being treated as an analogue for the player. It's great commentary on the way we approach games, and it does it all without disappearing inside it's own ass, which is impressive (though the LV and EXP thing still makes me roll my eyes).
Your answer and others have convinced me I need to check it out. So don’t be down on yourself. If group wisdom is a thing (spoiler alert: it is) you’re in good company. You’ve added onto the answers others had and more thoroughly convinced me to check it out. Thank you for taking the time to answer
Yeah the genocide route is what makes Undertale special. Even if you don't go for that ending you're still aware of its presence