I'd also highly recommend KOF if you haven't tried it. It's the kind of game that will directly help you with SF as well imo, so time spent checking it out isn't entirely "wasted" . The game is very rushdown centric with fast offense that makes you guess. Defense is often done offensively (jabbing out of pressure, etc) ala SFV. There are definitely huge differences, KOF has a handful of universal defensive mechanics for example, but many similarities as well - as stated rushdown, guess heavy, fast paced, fast and aggressive meter build your encouraged to is often, etc
The game had a massive 50 +/- fighter roster, you pick a team of three and rock out. XIV also does difficulty very well. XIII is kind of a byword for tedious difficulty in the fgc, but XIV doesn't continue that trend. You have to be crisp and precise, it's not SFV's (sfv is superior in this regard imo) ultra lenient input buffer, but it's far from some frame perfect mess of juggles and alternate timings. The game operates based on a few simple combo rules as well so once you learn your openers and your max cancels (usually your openers and maybe an extra command normal) you can kind of build combos on the fly to convert into damage without having to memorize 15 different, massively long combos. But! For input afficianados there is a ton of space to make basic combos longer and more intricate for more damage and better setups or positioning. A beginner can get more than enough damage to be relevant and not be left behind, and as they get better they can add in new juggles and tighten up timings to maximize efficiency, which is how a combo system should be built IMO. Easy to get in to but withroom to grow and add new elements as you improve.
The game had a small community though. Finding matches isn't really a problem, but you won't be able to just queue up. You have to find a lobbies or is Discord or a KOF forum to find players. The community is insanely nice though. I jumped into Romance's stream last night and had some dumb questions and he say there patient and polite and helped me figure out what I was working on, as did a couple members of his chat who were KOF vets.
I'll be honest, I don't think KOF had the numbers to be a replacement for SFV, but it's a game that absolutely deserves more press and credit than it's gotten. It's EXTREMELY well designed and has a very interesting and unique feel. It's almost like the speed and manic nature of an anime fighter with the grounded space control and footies of sfiv/3S and the rushdown offense of V. Super neat game.