When it comes to superhero rpgs, I've played and enjoyed a few of them over the years starting with Villains & Vigilantes and going through the Marvel Superheroes Roleplaying Game, DC Heroes rpg, Champions, GURPS Supers, and Mutants & Masterminds. I've owned and read numerous others, including Heroes Unlimited, Wild Talents, Silver Age Sentinels and ICONS. I'm about to give the Sentinel Comics rpg a whirl.
I don't think I've ever found the perfect supers game for me, though. At least, not perfect for what the 2021 version of me wants out of one. These are the things I think I'm looking for:
Low to Medium crunch. I'm not interested in rules heavier games like Champions or GURPS currently. I would suspect medium crunch games would probably give the best balance between covering what needs to be covered, but not doing too much.
Emulates comics. I'm interested in something that supports creating the sort of thing we see in comic books (or superhero film) not "a world with superheroes." Some of my following points sort of flow from this one.
"Every member of the Justice League gets to do something important." Older superhero games, to me, make the mistake of wanting to tailor attributes/power levels to benchmarks, winding up with disparate power levels. Sure, things like Karma/Hero Points address some of this, but in comics it mostly seems that power levels wind up being more about how characters tackle problems than whether they can tackle them. The Fantastic Four beats Dr. Doom, but so does the Punisher (or close enough). They just do it in different ways.
Heroic Normals are viable. Because of the ability score benchmarks, guys like Nick Fury or the Challengers of the Unknown tend to come out pretty samey in abilities because the normal end of the scale gets shortened. A system that gave them more variation would be nice. Of course, if you wanted a campaign of these folks, one could just play a nonsuperhero game, so this perhaps isn't as important to me as other points.
Variable Villains. Ever noticed how villains tend to be tougher or weaker depending on the hero or heroes their dealing with? I suppose it could be argued the heroes change and the villains stay the same, but anyway it might be nice if supers rpgs had mechanics for this difference.
Powers not overly detailed, but not quite freeform. Honestly, I lean toward more of a "just tell me what is does take", but you need to certain mechanics attached to powers to use them in the game, and you also need suggestions for people modeling powers, so for that it seems like completely freeform isn't the way to go.
Supreme effort. This is one supers games seem to consistently pick up, but it bears repeating. There should be a means of a hero giving it that extra oomph in a dramatic moment.
There's probably something else I'm not thinking of, but that's all I've got now.