You mean overall textures right? And lighting and everything else lol. 

Really tricky to come to a graphics discussion and talk about personal preferences 

I agree with your statement. It is interesting to see what people can do with other engines. However, as Unreal seemingly takes more and more market share (at least market share of the big games) This should create something of a virtuous cycle where there are more people working with the engine, so more people coming up with ways to push it, more people experienced with developing for it, and the like, so the games made for it should be better than those for other engines, all else being equal.  

Of course, all else is never equal. But, I think you get the point. It is interesting to see people work with other engines. But, Unreal has proven to be great, and there are just more and more people that can do a great job with it. 

In terms of marketshare the Unreal engine probably has less marketshare than it did 10 years ago. In the 7th gen Unreal engine 3 was everywhere, but in the 9th gen the big publishers like EA and Ubisoft moved towards relying on in-house engines instead of Unreal. Square did the reverse, moving from an in-house engine that gave it a lot of problems in the 7th gen to using Unreal for many of its biggest games now.

Since the Wii, Nintendo has made gameplay the priority. And, likewise, their fans seem to be okay with it. So I'm not sure there's much point in analyzing the technical merits of their games.

Not only ground textures, but it also wins on (overal) textures, lightning, effects... and on Switch I believe FF12 also runs in 900p, so it's also a narrow win for the FF on the resolution department...

It's not that Final Fantasy 12 is ugly or anything, it isn't, but it's a 15 year old game uprezzed vs. a game made from the ground up using a modern engine using better hardware than what was available on the PS2. It's fine to have your preferences, really... but objectively Pikmin 4 is way more advanced game graphically speaking. You can even say it's a graphical showcase for the platform.

Are we talking about what's visually appealing here, or technically impressive? They're two quite different things.

It's fair enough to prefer the look of FF12 artistically, but in terms of graphics technology, Pikmin 4 is about a generation and a half ahead with its use of UE4's lighting, materials, effects, etc.

Technical merits affect gameplay, at least to an extent. A high and constant framerate is valuable in action and platformer games where precision is key, high resolution helps in games like Pikmin where being able to zoom out and make out details helps inform players, lighting and shadow effects help shape the environments in games like Metroid and Zelda, etc.

*Since ever, way before the wii they consolidate in the industry by the gameplay value of their ips, not because they were aiming to have the best graphic performance over the competition.

Plus it is neat to follow the graphical evolution of their ips, nobody would be okay if they stagnated with wii graphics till today lol

Yes, it definitely does (affect gameplay). But none of it seems to matter with Nintendo games. Thirty frames, sixty, 720P... Nintendo games these days sell regardless. So I just don't see the point, other than just analyzing for analyzation's sake... which is fine. But Nintendo seems to live within their own bubble, and their games likewise sell within their own bubble. They've created their own world, and their fans seem to be happy there. 

I'm not sure if people being apathetic towards game performance is specific to Nintendo's fanbase. Games in recent years like PUBG, Battlefield 2042, Cyberpunk 2077, the GTA Trilogy, and various Ubisoft games have had technical and/or performance issues while still selling millions of copies.