Monitors are personal items. Can't really choose between flat and curved for you, you'll have to actually look at them and decide for yourself. I personally do not like the smaller curved monitors, for a 24"/27" I prefer flat. A 35"+ super-ultra wide is a different story.
You'll also need to decide what kind of screen. IPS gives much better colors, much better viewing angles, so overall a much better picture. VA screens are not quite as good, TN screens are the standard 1080p type where if you are a few ° off center, it gets terrible looking. TN is generally the cheapest, but also the fastest, best for high-speed first person shooters, IPS is generally the most expensive, and slowest gray-to-gray, but has the the best quality picture, which is better for open-world or strategy games. VA is a compromise of both.
I'd suggest you go to a place that sells computer stuff and has monitors you can look at, decide which type suits you best, then go find what's best or at least decent for your needs.
You don't buy a car until after driving it and seeing if it's comfortable and fits. When you are 6'7" tall, I don't care who tells you just how good that little Honda Civic is...