Fight n Rage is damn near best in genre, but it does run a little long for how intense it is. A truly excellent game.
Double Dragon Advance is one of my favorite classics.
Sengoku 3 comes highly regarded.
If you can get over the mocap, Streets of Fury EX is an incredibly technical and fun brawler
https://store.steampowered.com/app/350910/Streets_of_Fury_EX/ The guys who made this, with only this game in their resume, were tapped to make Streets of Rage 4. The game plays like the sequel to Guardian Heroes we never got.
For classic Streets of Rage, I really think there's no reason to play anything but Streets of Rage Remake at this point. Only the most pure of the purists would find fault in SoRR.
Dynamite Deka/Dynamite Cop/Die Hard Arcade got a real nice Sega Classics remake on PS2 which emulates really well. Certainly not a great beat-em-up but a delightfully fun and dumb one.
The D&D Mystara bundle is definitely a good grab. Capcom Classics is more of a nostalgia grab though.
https://store.steampowered.com/app/269230/Aces_Wild_Manic_Brawling_Action/ Aces Wild plays a bit like if Treasure made God Hand in an absolutely stupid and over the top manner.
If you want to get down to the fun and good but not great tier,
https://store.steampowered.com/app/587180/Wulverblade/ Wulverblade is a nice historical themed classic style beat-em-up while Shank 2 is a cross-breed beat-em-up with some platforming, weapon switching stylish action. Shank 1 is good too but 2 is a better product for gameplay.