I know it's a matter of preferences, but I can't believe how people say Guilty Gear is this impossibly gorgeous game. I just don't see it - sure, it's impressive that they made 3D look 2D, but that doesn't mean it looks good. It's a garish over-designed mess with impossibly ugly character designs IMHO, it's as if everyone was Sylvie Paula Paula (officially my most disliked character in KOF history, lol) levels of terrible. I vastly prefer KOFXIV in terms of looks, no question.
I prefer KOFXIV visuals as well, mostly because Guilty Gear's extravagant hit effects make it harder to follow the fight. I also find GG's moves are difficult to discern their hitboxes.
I think GG is to be commended for retaining the series look and feel so faithfully though, obviously a lot of care went into making it appear 2D. In those terms it's probably top dog, but i'd put KOF right behind it in that regard. XIV is actually a lot closer to XIII than people give it credit for. Things like the animation, movement, size of the characters, hit effects and the field of view/camera is almost identical and it really helps to make it feel like KOF. The faces even have a bit of "Shinkiro/everyone looks the same" going on like the earlier entries!
At the same time, some of those are probably why a lot of people find it unattractive. Faces are definitely a sticking point for a lot of people, and large character size can give a much greater impression. SFV has chunkier characters but it makes the stage feel smaller than it should. It doesn't quite feel like the old 2D games because the camera does things like pan up when you jump. MK/IJ's camera is like the TV camera in a soccer game, panning along the side of the stage but never reaching the end, instead angling outwards to the far side. It looks more dynamic but I find it a little off-putting, and is one reason it doesn't look as 2D as GG or KOF.
If you look to Tekken, the characters are right in your face taking up most of the screen and you can see heaps of details (pretty much the way it's always been in 3D fighters). XIV characters look a bit dinky by comparison, and you can't as easily see the (pretty finely textured) details. Some are so finely detailed they start to (unfortunately) moire at the standard zoom level. But that zoom level is important for KOF gameplay, hence why they changed it from XII to XIII. Maybe a new Art of Fighting or Samurai Shodown can be more impressive to the casual onlooker, since those games have zoom in their heritage! Tekken's also gone nuts with crazy hit sparks, KOF has very minimal ones, easier to see what hit you. Personally i always preferred Virtua Fighter's aesthetic to Tekken in this regard, since nothing is ever obscured.
I'll give it that lighting and shaders etc is hardly XIV's strong suit (especially if you compare to Tekken). But again i'm not opposed to it looking basic, when it means everything is super clear to see for gameplay. If you look at MK, their characters look more like they're part of the scene, but almost to the point of blending in too much. Throw in the darkness of most levels and it becomes a lot harder to follow. This is one aspect i actually prefer in XIV over XIII too. XIII had stages that cast shadows over the sprites. Coupled with some muted colour choices, it felt like lots of characters weren't even in their iconic colour schemes.
When you're talking stages, XIV has some noticeably low polys and weak textures, but a lot of them manage to look great regardless, look very "SNK", and would be right at home in a sprite based KOF. Personally i think it has more good stages than XIII did, and certainly more than SFV. GG probably takes the cake here again though.
Sorry for the long rant but it sucks people are missing out on this game because they're hung up on the visuals for whatever reason. Even if you truly hate the visuals but you like fighting games, you should absolutely give the game a shot. With 50(+4) characters, a heap of excellent stages, fantastic music, and some of the best fighting gameplay around, the value proposition is most definitely there. For me, i'm wavering on this becoming my favourite 2D fighter of all time, so we're talking dethroning classics like SFA2, KOF98, Garou, SF3 etc. It's damn good people!