What's your budget? What kinda games do you like? If you like quick twitch competitive first person shooters, then a 1440p/144hz panel may be a better choice. But if you like more RPG games, then 4k/60hz is really nice as well.
I have a 4k/60hz panel and a 1080ti and gaming on it is a dream. Some people like the higher refresh rate than 60hz, and for that I use another monitor.
Pending your budget, ultrawide is a great option. It has more pixels than a 16:9 panel and still has a 100hz refresh. The extra real estate on the screen really makes for an immersive gaming experience. An the 1440p resolution is a good pixel density where you can have 3 or 4 webpages open at once and see them all at the same time. But ultrawides are expensive, but hey are nice. This AOC checks all the right boxes and is a good bit cheaper than the Asus or Acer variant.
PCPartPicker part list:
https://pcpartpicker.com/list/Z3yMYr
Price breakdown by merchant: https://pcpartpicker.com/list/Z3yMYr/by_merchant/
Monitor: AOC - AG352UCG 35.0" 3440x1440 100Hz Monitor ($899.99 @ Best Buy)
Total: $899.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-12-13 15:18 EST-0500