My problem is that I'm a graphics snob, and Empyrion is just too "primitive" for me in graphics and sound. I'm not talking "cartoon" graphics, like some call NMS (though it can be downright photorealistic in places) or even Overwatch, as these are artistic choices. I'm talking about dated year 2000 graphics. Even Space Engineers with its Lego blocks looks so much better IMO.
BTW, I actually own EGS, so I'm basing this on my own experience on hardware that can easily handle ultra settings in such a game. I just rather play SE and NMS (and X4) instead.
I agree regards graphics, but I'm more for gameplay.
I have around 2400hrs in SE, I love the game.
NMS over 1500 planets visited (from day one). It is a very good game.
X4 tried it, no planets means a no go really.
Empyrion graphics are a step up from Evochron, but even Evochron has the gameplay some of the other titles lack.
SE is by far my favourite space game, building, travelling and indeed scale are second to none, no other space game comes close for those things. However unless your running an ai mod, it's pretty lonely out there (but I must try the new ai mod out now). Even if you do run an ai mod, it's still lonely with no npc's to make fun of.
With NMS I sort of run out of things to do, or it seems like that. But I'll go back, I always do, for a while at least. Some of it's planets are fantastic.
SC is beautiful really, but empty, it suffers from what ED did, pretty shallow, gameplay wise.
I have to be in a game where I can build my own ship now. When I got SE in early 2014 it gave me the bug (pun intended), I just had to build my own ship.
So it's either SE, Empyrion, or I guess Starbase (I'll pass on that, no planets again). SE for building without a doubt, but Empyrion for a rounded game. For me anyway. The building isn't bad either.
All the games mentioned (other than starbase not played that), are great in their own way. But if a space sim is what your after, few fit the bill, Empyrion (if you can get over the lower graphics) is a very rounded space 'sci-fi' sim, imho.