New
#11
An R9 390 or GTX 970 might be good, I have personal experience with a NVIDIA 970, but I paid less for it three years ago than you can find it new now. Here's a video showcasing 60fps settings for that card (can vary) GTX 970: XCOM 2 - Settings for 60 FPS - YouTube
The cryptomining and the RAM shortage are killing the market, it's not worth upgrading unless you really want it. These older GPUs are rather expensive, and honestly, unless you can find a good deal on a used card, it's not worth buying old gen cards, as they're not as good of a value for gamers. The new NVIDA 11 Series are coming out somewhere within maybe August-March 2018. If you're willing to wait, it might be worth it, but it might be even worse by then, and buying anything might be implausible. Although, it could be better. Buying used cards has some risk associated with it, but you might be able to pick up a card sufficient for what you want for $100-200 if you're lucky. I'd recommend buying new, though, for longevity's sake. The 1080 Ti is a great value (even now) but it's $799 and would bottleneck if you didn't upgrade your other hardware. A good budget card is the NVIDIA GTX 1060 6gb at only $300. Maybe even consider getting one used if that's worth the cost to you. A GTX 970 is worse (not horribly) and is potentially MORE new or is less than 50% less in most cases used.
These aren't always the best, but it illustrates my price to performance point:
http://gpu.userbenchmark.com/Compare...6GB/2577vs3639