PC monitors of all kinds.
People keep mentioning just the size, but IMO the aspect ratio is also important. I wouldn't get a curved 16:9 screen regardless of the size, but for 21:9 or wider it starts to make sense.

I had Alienware's 32 inch curved monitor for a day (had to return it due to yellow discoloration on one side of the screen) so while I didn't get to use it that much, I could imagine getting used to it pretty fast, though I personally would prefer a smaller curve.

In general, though, if you're asking "is there a massive benefit having a curved over a flat screen" I'd say no - it's not "massive", it is there and if you'd go for one of those super ultrawides like Samsung's 49 inch 32:9 screen then a curve would definitely be necessary, but other than that I wouldn't call it massive. If you're thinking about a regular 27 inch 16:9 screen then forget about the curve, get a flat panel.
Might depend on the size of the monitor. I've gone from a 23.8 inch flat to a 24 inch 1800r 144hz monitor and the difference is honestly unsubstantial. If it were say 27 inches or greater it would perhaps be more immersive, but I can't confidently tell you to what degree. I will add that going back to flat panels after being on a curved monitor makes the edges of the screen seem further away.