Pretty convenient for you to forget Samurai Shodown (1993), easily one of the most innovative fighters/series ever.
Kizuna Encounter was the first tag fighter ever.
There were plenty of mechanics introduced in SNK/Neo-geo games that are considered the norm today. To dismiss most of the games as clones is simply ignorance.
The only SamShowdown game I've played is VI, which I thought was average at best. I did buy the Last Blade 2 though, but could only find enjoyment in it through the secret character.
And KOF 94 launched two years before Kizuna Encounter and one year before Savage Reign, IIRC, so I think that was fun. I do enjoy KOF though, even if the early ones are very rough, they still are 1000X more enjoyable than the other fighters I just cannot stand. World Heroes, AOF 1/2, Ninja Masters, so many of the early ones are just unfun to play, even if some of their mechanics stuck in the genre. Being a clone isn't a bad thing in itself, but it's undeniable that SNK and Capcom took cues from each other constantly during the 90s and a lot of their games feel samey until the late 90s. Heck, even Garou, which clearly took some cues from SFIII, felt fresh enough that I vastly preferred it to any version of SFIII hands down, and I'm curious about Double Dragon and Revenge of the Dragons solely because I'm wanting to see how Technos' efforts on the NG went, after a good period in the arcades.
Heck, with the Capcom point brought up earlier, playing their beat em up collection drove that point home as outside of Battle Circuit, a lot of the games felt very samey and made on the same engine, with really very little to feel different enough to be engaging. And for arcade games meant to be score chasers, that's not really fun compared to something like Magical Drop III or Puzzle Bobble. I can play those two games constantly (MDIII is easily the most played ACA Game ever released for me) but fighters I don't see much reason to after I beat the main game with every single character in the roster. (Though for KOF, that does take a while) Thus seeing how many of them we've gotten in the past few months (and how they keep releasing KOF games that aren't 2003 despite that being the newest they can port and the one I'm waiting to buy on Switch the most) just feels like fatigue more than anything, I'm sorry.
I'm just waiting to see if they'll release any cool platformers like Spinmaster and Magician Lord since it's been a very long while since the last one. I got Top Hunter ages ago and I don't think they released another besides Blue's Journey (Which I have on my wishlist)