I have a fondness for DC Heroes' exponential system, and an appreciation for M&M's sheer weight and support. What does it for you, and why?
I love the concept, but hated the game...
All the supers games I've run or played, favorite to least:
- Sentinel Comics - love the way it works, the presumptions of success, and the fail forward advice is worded particularly usefully.
- Marvel Heroic Roleplay (MHRP) Best Marvel Yet. Much the same reasons as Sentinels
- Advanced Marvel Super Heroes (AMSH) - About as narrativist as Trad Games from the 80's get. Lots of forward looking elements. The color table is brilliant. First game with a resources roll mechanic I liked. Note that "advanced" is a misnomer; it's really "2nd edition"
- (basic) Marvel Super Heroes - the resource point mechanic and fixed numbers per category are why this isn't above Advanced.
- Champions (but note: I've only used it in the fantasy hero mode as a GM, and only done supers mode as a player) The most flexible trad game ever.
- Marvel Super Heroes Adventure Game - Fun for one-offs, easy to run, but lacks meat for campaigns.
- Spirit of the Century (the way we played, it turned into a pulps supers game, influenced by the Watchmen movie) Once was a hoot. We enjoyed it, but none of us wanted to run that setting again. All of us were willing to play it again.
- Car Wars (using Autoduel Champions section 3) - Car Wars in RPG mode is brilliant. Adding Supers (and the magic and dragons rules) is a lot of fun.
- Villains and Vigilantes - too much of the "incomplete due to early design standards" for me when I found it. Great adventures, mediocre system.
- TMNT (palladium) Not a good system, but a great adpatation of the setting to that mediocre system
- Heroes Unlimited (Palladium)
- The Fantasy Trip (original) with the supers article. unfun++
- GURPS Supers 1e Unfun and math-intensive
- Mayfair DC Super Heroes - unfun, unintuitive, math intensive, too abstract
- Mutazoids - My god, the formulae.
- Marvel Universe - I hate point pushers.
Superhero Adjacent games (where they'd fit if I considered them true supers):
- (NR) John Carter of Mars (John is a super, as would be any other Earthperson present on Barsoom) (not run yet)
- (3.5) GW Judge Dredd.
- (4.2) Battle Born, G/Sol, and IoS&RG (Better Games - Everyone's in battlesuits.)
- (4.5) Tails of Equestria (I've run multiple 1-shots. Everypony is a super to some degree. But it's not in the Supers Genre)
- (5.5) Deathwatch (FFG 40K) (all the powered suits)
- (5.6) other FFG 40K RPGs
- (7.1) CP 2013 (many PC's are street level supers for power levels)
- (7.2) CP 2020 (ibid)
- (7.3) Shadowrun 1E (ibid) More supers than Cyberpunk, but not as good a game engine.
- (7.4) Shadowrun 3E (ibid)
- (10.5) Judge Dredd Traveller
- (15.5) Judge Dredd D20
The ones I could be convinced to run again as multi-adventure or extended adventure campaigns:
- Sentinel Comics (am about to restart my pre-Covid campaign)
- MHRP
- AMSH
- Car Wars w/ADC
One Shots only down the road:
Undecided (games I have but haven't used for supers despite rules for supers, or supers games I've never tried but would someday like to):
- CORPS (2e, generic engine, has a robust powers system I've used for fantasy.) Would be interesting to try as a "street level" game.
- EABA 1e (I playtested it, and used the powers system for alien abilities, but it supports much higher levels of power than I used)
- WEG Batman
- D6 Supers
- TORG (fan expansion for supers built upon the Nile Empire mechanics for pulp supers)
- Genesys (if it gets a supers expansion, which I do expect)
To some extent, I consider D&D and Pathfunder to be "medieval super heroes", all the way back to AD&D 1 and BX. Especially before the idea of NPC Classes with levels. (Which goes back to the 1970's... in Dragon... it didn't hit core rules until D&D 3E, but it was present for late 0E and AD&D 1E in magazines, and in 2E in an expansion book.)
Edit note: I got distracted by nature, so saved, and came back to complete the answer.