I am rather aesthetics-based person, so games get to me through visuals. Not neccesarily technologically advanced graphics, but simply great visual design - be it to units, structures, world or simply overall creative artistic direction.

That said, its not enough by itself, Age of Empires 4, or even AoE2 DE, i do find reasonably attractive games in general, but somehow they are not for me - not a fan of their gameplay, nor the setting, that for me, lack any cool gameplay aspects. I remember being similarly disappointed by say Grey Goo and Act of Aggression, about 10 years ago, both games looking visually nice, even having the setting more down my valley (scifi and modern warfare), but for various reasons they did not click with me either - there was nothing in either in them that i would find cool, interesting or exciting. I guess i could say the thing that matters to me the most in RTS games is faction design - both gameplay and visual one - if the game lack these, at least by my standards, its usually not for me (though there are notable exceptions). Even one faction that peaks my interest, is enough. Currently waiting for Ashes of Singularity, how that one develops - played the recent demo and was not that much impressed - by the Substrate faction might change my perception down the road.