My biggest recommendation is to go to the store and plug in and see what you like. I found the LG's to be the best calibrated out of the box (still haven't touched the settings), whereas the Dell's couldn't differentiate well with shadows and white/light grays. There's a lot of great options out there, but once you go with an ultra-wide you won't go back.

I thought the curve was gimmicky at first, but after testing the flat, it's needed. The flat is so wide that is blurs in your peripheral vision and the color accuracy dips at the edges of the screens. The curve is just subtle enough to fix all those issues and your brain adjusts after 15 mins. It's weird at first, but you'll love it in the end.

Best of luck on whatever you choose!