Honestly, there are a ton of old (and a few new) champs that really could use some love from buffs. Most of these really need a solid rework or reasonable numbers increase. I would appreciate any of them, but I've made a habit of making my Profile pic whomever I want buffed next. Originally I made it Red Mags, before I even knew he was up for a buff, and then he was a banger (and my first rank 3), then I switched to Venompool, who I'm expecting to get a pretty sick buff next week. I think next, I'd prefer Electro. He's annoying on defense when he's a mega-stacked healthpool boss, but pretty boring other than that, or when shocked. He has some cool potential with his abilities, electricity is super versatile, but it would also not be that difficult to make it apply like poisons with Abom or something.
Mystics:
Dr. Strange
Iron Fist
Juggernaut
Loki
Thor (Jane. Foster)
Unstoppable Colossus
Cosmic:
Air-Walker
Black Bolt
Captain Marvel (OG)
Drax
Groot
Ms. Marvel (not Kamala), I forget that she's in the game all the time
Spider-man (Cosmic)
Superior Iron Man
Thanos
Tech:
Green Goblin
Iron Man
Iron Patriot
Kang
Red Skull
Yondu
Mutant:
Beast
Cyclops (OG)
Cyclops (Blue Team)
Deadpool (X-force)
Nightcrawler
Storm
Skill:
Agent Venom
Daredevil (OG)
Elektra (literally forget she's in the game on the regular
Hawkeye
Karnak
Korg
Moon Knight
Punisher
Winter Soldier
Science:
Captain America (OG)
Captain America (WWII)
Electro
Rhino
Sentry
Spider-man (OG)
Spider-man (Miles), who I know is supposed to eventually