To be honest there are MANY "best looking fighting games" this gen, depending on their particular bent. Most of the games aren't competing directly with one another for art direction and overall style.
SC V has incredible textures, image quality, and great art direction for armor and background detail.
DoA5 looks to have great animation, character modeling, active backgrounds, smooth lighting and shadowing.
Tekken Tag 2 has super high poly models compared to most, really solid backgrounds, really rich, popping colors for a 3D fighting game that doesn't invoke a cartoon style.
Mortal Kombat has that chunky, modeled look down cold which gives it a unique look among every fighter this gen, with extremely good backgrounds for atmospheric effects and dense artistic detail.
MVC3 has the comic book/manga look well in hand.
SFIV and SFxT piss some people off because they're so colorful, but they've got extremely detailed animations with the most articulated characters, and a unique colored marker art style with very creative and explosive stage animations.
Hell, even VF5:FS with its weak texture quality, beats almost every other game in terms of sharp IQ plus its quality and detail of realistic style animation.
Basically, this is a great generation for fighting games that use some form of 3D graphics.