I've had mixed results of late. I had a doublesight 26" IPS that was excellent until the flourescent backlighting started bleeding through blacks.

The one I had a bit ago was the best I've had for black-levels and long gaming sessions re: eye strain, though it didn't have G-Sync. It was an Asus PB278Q. I've seen mixed reviews on Amazon, which seem to indicate there are different models of it that they ship, some better than others.

As for FPS, I can attest to how much smoother removing the maxfps option in WoW is and letting it get up over 100 even though my PB328Q's I got for Christmas only do 60Hz. They are OK for black levels, and I needed a bigger monitor as my eyesight has started to suffer the slings and arrows of 20 years behind a monitor. Having had them for a few months, I can say the next monitors I get will need to have G-Sync capability; I'll admit to not having used any of those but if I'm reading things right, that will fix the tearing problems I see on these. I can live with it, but it would be nice not to have to.

At one point, I'd have said the Dell UltraSharp IPS panels were probably the best visual quality going for general purpose use. Honestly, though, I haven't done a bunch of research lately as what I have are good enough. The last big monitor thread that got me some really good buys was over on Anandtech. That thread is pretty obsolete now, but I'm sure they'll have some good info. https://forums.anandtech.com/forums/displays.72/

My 2 copper, anyways. Good luck!