Back in the day, I used to have no compromises: Just the idea of lowering one thing from "Ultra" to "Very High" would feel like a betrayal to what was possible, so an upgrade was always on the table. But at some point I realized there were other things I could spend my money on in life other than a video card with a terrible price/performance ratio. So there are certain things I'm willing to sacrifice to play a recent game and certain things I am not.
My most likely sacrifice: Any of those fancy Ambient Occlusion methods above SSAO, especially the hardware-based ones, is the first thing I lower if I have to lower anything, because I find nothing eats up your framerate more than a lot of them, and I find the differences are usually so subtle I only notice them in screenshot comparisons online, not when I'm playing.
My least likely sacrifice: Anti-Aliasing. I can play a game where the shadows aren't great or the draw distance could be better, even if it annoys me a bit. Hell, in single player games, I'm even willing to lower my framerate. But nothing is more distracting to me than those weird jagged edges and strange shimmering effect. Conversely, playing a game that is either old enough or low-polygon enough to run at 4K on my TV or using supersampling on my monitor is a treat because it gets real close to making me feel like I'm playing an interactive animated film rather than a pixellated video game.