I don't think you're actually being objective about Thanos' VFX though. It's all well and good to imply that Darkseid looks better because he is like an orc but that doesn't mean the vfx is better. One of the many praises given to Infinity War/Endgame is how they managed to make a fully CGI villain seem realistic, both in terms of character and design. If Darkseid is like an orc, Thanos' design is more in line with the Naavi, in that the designers and artists managed to craft something realistic. The way his face moves and they way they managed to fully capture Josh Brolin's personality and movements is no small feat. I think most people would agree that Darkseid didn't manage to get to that level simply because he hasn't had a whole movie to do so, only a couple of scenes.
I would argue that Darkseid (as Uxas) didn't look as well realised as Thanos did in any of his battle sequences, but again, Thanos had the benefit of a whole movie being about him. I guess to me, what's remarkable about Thanos is that he looked realistic. He was shown in different lights and environments throughout the films, which actually showed that there was an insane amount of work put into him - from the opening on the Asgardian ship, to the Collector's collection, to the red scapes of Titan, to the bright daylight of Wakanda we got to see Thanos look real. I don't think Darkseid had this, because we only got to see him in dark lighting - even when he was Uxas the light was pretty muddy, and then on Apokalips it was a kind of brown-orange light.
Honestly, it sounds like your problem is with the design of the characters, not the VFX themselves. If you like Darkseid's design because he is closer to an orc than a real person, then that's cool, but it's not the vfx you have a problem with. And even then there's no point in comparing them, because they are not reaching for the same goal.
Marvel's (and DC's) CGI can definitely be a mixed bag - Black Panther, I'm looking at you - but man, Thanos is brilliantly rendered. Corridor Crew talk about him in detail in this and their video on Endgame.
https://www.youtube.com/watch?v=HWnRuPZ1Exg&t=70s