Ultrawide monitors are an interesting class. I fell in love with them about 4 years ago when I got the LG 29UM58. I got that monitor because my current rig was targeting to run games at 1080p/1440p. I liked the idea of having the wider view point without having to pay for the extra cost in vertical resolution like you would with a normal 1440p monitor. I've had that monitor as my primary monitor for roughly 4 years now.
Just this past week I upgraded to a LG 34gk950f. I am in love with this monitor. As reddit said, it is the king of the ultrawide class. 144hz, 1440p, 1ms response time, enhanced A-sync for Freesync2 and G-sync compatibility. The monitor has it all and more.
With that said, you need to experience gaming on an ultrawide first before really making a decision. I instantly fell in love with mine because it brought me back to the old days of where I played CS1.6 with a CRT monitor right up against my nose. Ultrawide monitors give you the same breath of view point without sacrificing your close vision. Other people want other experiences, this is just mine.
When it comes to curve vs no curve, I'm partially in favor for no curve. Yet these are getting harder and harder to find as the panel size increase. I've noticed with my LG 34 curved, that the field of view (FOV) seems a bit more pointed than it used to. I need to play around with games like DOOM and more to really see if its just adjustment of FOV, a trick in the human eye, or something to see really what the difference is. But so far this is my only complaint, and should be minor as most games have a means to change FOV.
As you can see, I am very biased towards LG and their monitors. I think their IPS panel creates the best picture. As they venture more into HDR, I think they will have some of the best monitors in the coming years. I used this website to figure out which monitor I was going to upgrade to:
https://www.displayninja.com/new-monitors-in-2019/
It lists all of this years models, so depending on your budget, I'd suggest looking through this list and seeing what fits you. I've heard great things about those that use the AUO VA Panels, so Acer ASUS, etc. Dell also makes great monitors with IPS and Ultrawide, but they can be a bit of a higher price. Next up would be Samsung and LG on my top list. Both companies make their own panel which is very rare these days. They also have the best Ultrawides in my opinion, as they will obtain the higher refresh rates that you need for today's games.