Here is a way I found to IMO greatly improve Anti-Aliasing and image quality in the game, and which I haven't seen mentioned.

Basically, I think the 2 AA modes the game has are total garbage. I play at 1920x1080 and the game's AA makes everything blurry; textures and shaders lose a lot of detail. If you don't believe me, just deactivate AA and see how sharper the textures and shaders look (for example, the wet rooftops in Skara Brae Above look much better). So, what I do is deactivate in-game AA and use ReShade for AA. Personally, with ReShade I just use SMAA and a bit of LumaSharpen (less intensity than the default). But ReShade has options to suite every taste.

WARNING: if you deactivate in-game AA, everytime you restart the game, AA is re-enabled (even if it says it's disabled). This keeps happening to me as of Patch 2. So I have to manually disable AA each time I start the game, by enabling AA, and then disabling it again.

In inXile's defense, I have seen this AA quality issue in another UE4 game (Obduction), so I guess these must be some crappy default AA modes in UE4. Still, I think the developers should be able to tweak and improve the quality, since many other UE4 games have better image quality in this regard.

Never even thought to check what the game looked like without the TAA. It looks way better! With the in game TAA it looks like a film of jelly is on the screen.

I probably didn't notice because I was running Reshade with adaptive sharpening.