Which GPU to buy?

I recommand you an RTX 2080 for good perfomances.

i recommend by ryzen with vega11 (cpu with discrete video) and wait until crypto hype calm down. i think its take 6-8 months, after that tons of cheap video cards gonna flood market (ebay/amazon) and prices for new cards start shrink too. At this moment any modern game runs 720p & mid/low settings around 30-40fps on vega11.

I think 1080 ti, it's very not bad GPU