MKX is going to feel a lot like MK 9 when compared to other entries. I didn't play anywhere near as much of it, and never got good at it, but from what I can remember it builds off that as a base for the most part. So, if you liked 9, you should like MKX. It has a lot of additional single player content as well. There are lots of towers, including ones that rotate and are holiday themed. Most of them I think are locked to the medium difficulty level which usually goes down as long as you attack like a rabid animal with mild damage combos (20% range). They can get tricky if they have lots of fight modifiers on them which exist.

There is stuff like bombs, freezing punches, insta-kill x-rays, tilting levels, damage on jump, and exploding teddy bears (that one is a secret or something though) And like I said, I got close to everything but Goro (which is a stand alone buy) for 30$ during a sale by getting the premium edition during a sale. That includes the classic skins you referenced. Predator is really well represented, so if have an interest in him, it's another reason to consider that version. It will have some stuff you may not care about, but getting it on sale will still probably work out cheaper than buying an item or two by itself. We may be in a sale drought right now, but they don't usually last too long.

If you haven't already looked into the older SF games (SF2 Champion Edition specifically) they ran at a much slower pace than most fighters do now. They are less about crazy combos and lots of crazy options and more about getting in a few good hits. Something to think about if you ever start to feel newer games are a bit complicated or fast paced.

Capcom vs SNK 2 is Dreamcast, PS2, Gamecube era. I have the Dreamcast version. The Gamecube version could be interesting in that they released it later and from what I remember they added some some input helpers in the game to try and make it more accessible. I don't know if they helped much or not.

BTW, Injustice is really good, but it's a bit different. Its a little unforgiving on directional inputs compared to MK, and it only has 3 real attack buttons and a fourth for unique character traits. One of the attack buttons also is more of a universal "launcher" button than a formal attack button. That can be really confusing if you just jump in and want to start pressing buttons. The system is fine if you spend some time with it, but I'd say it's one of the harder fighters to play ignorant in. Everyone is so cool in the game that I wanted to play everyone. It makes it really hard to pick just one or two.

I've thrown a lot of info at you, so I'll just let that sink in and you can go figure some stuff on out for yourself. But as a final note. MKX is pretty demanding on the hardware. Be sure your rig is up to it. Mine plays Injustice at max without a hitch, but I have to turn stuff down on MKX and lower my resolution to keep it running at 60fps. On the other hand, you can slow the game down a little by running the game at settings that are too high. If the game feels too fast, that is a hack to play around with.