Looking to spend around $400, with wiggle room. Gaming will be the primary use, movies and TV secondary. Currently have 1440p 165Hz G-Sync and would like to have the same. 27" is the preference but I'm interested in ultrawides.

I currently use the Dell S2417DG. It is infamous for a color banding issue it was plagued with back when it was new. I RMA'd the monitor twice before I settled on an acceptable one. Thankfully I have learned to live with the banding and gaming is great with the 1440p 165hz and G-Sync I take advantage of. I never notice the banding in games.

I've been eyeballing the new Dell monitor king, the S2721DGF. It is IPS, uses LG's nano-IPS panel and is also 1440p 165hz. It is G-Sync compatible certified which is a must since I have a 2080 Ti. I can pick it up right now for $300 with coupons. As far as I can tell this monitor is the best in the league including for color work. Once the settings are optimized it will be excellent.

Should I jump on this? One of my hesitations is that I have been satisfied with the S2417DG once I learned to overlook the color banding. I notice it when watching shows and movies for sure, it's certainly unattractive. One of my regrets has always been that I went 24" and not 27". Also, at this point I don't know if there are any truly great ultrawides that won't cost twice this amount.

Final question. I'm looking for advice on selling the S2417DG. It is truly in mint condition. It still has the protective wrapping on it which I never removed due to a little OCD possibly about scratches, original packaging and documentation. The monitor itself has zero problems with pixels, backlight, buttons etc. Could I hope to get $250 for my monitor? Maybe sell it on Craigslist or FB Marketplace? I don't think I need a secondary monitor unless you can give me ideas on how to use it.