Personally, I'd opt for the PC version, but my reasoning might not really apply to you. My biggest reasons for choosing PC for my play through is because of ultra wide support, mouse + keyboard, and loading speeds off of my M.2 drive (I load from a fast travel in no longer than 3 seconds.) I really believe the Foliage Visibility setting and Terrain Quality on Ultra make a significant difference in Velen. I really feel lost and immersed in the vastness of the Velen forests, wherein the console versions, I'm missing that feeling which is something I value heavily. (This could be heavily reliant on the ultra wide resolution and not the graphical settings.)
As you know, your PC setup is no joke. There's no refuting the obvious advantages to playing on a PC, BUT I noticed you own a 1080p/144hz monitor, and in that case, I'm choosing the Xbox version in your situation. HDR with the checkerboard 4k visuals, in my opinion, will impress you.
Witcher III + Expansions is on sale for $19.99 on GOG right now (or buy it on steam and test it for an hour, if it's not impressing you then refund it!), and the Xbox version can be found for around the same price if used. Therefore, the best way to find out would be to try it out on both because everyone has different opinions on what is important for their gaming experience. If you do, make sure to give an update on your thoughts. :) I'm only running a GTX 1070 at 1080p - 21:9, so I'd be curious about your experience with your rig!
In the end, Witcher III is going to be amazing either way. I understand you want the best experience possible because I was chasing that feeling too, but no setup will ever be quite enough in my experience. Just enjoy yourself!
