There are a whole lot of ways to approach that question, and I'm sure there's no objective best monitor, but I may as well throw in my recent experience on the subject:
Very recently I bought a new monitor. I watch a lot of streaming TV and movies at my computer, but I also play a lot of fast-paced FPS games.
My ideal monitor would have vibrant and accurate colors while also having a high resolution and supporting at least 120Hz. Throw in G-Sync for bonus points.
As luck would have it, I found a monitor that ticks every last one of those boxes. The Aorus FI27Q is a display I've only had for a little over a week now, but it's gorgeous. Its IPS panel provides vibrant, but not oversaturated colors, and it's a 1440p display -- all while supporting all the way up to 165Hz (although I've read the panel provides real-world performance closer to 120Hz).
It supports AMD Freesync while being certified G-Sync Compatible, and it's just altogether fantastic to use regardless of gaming or anything else.
I paid around $590 after tax for it, so it's also within your budget.
That said, do NOT buy it just because of my recommendation. Rather, keep this in mind while you're searching, and even if you're interested in the model I've just gushed about, definitely look up reviews and specs.
EDIT: I've just seen in the other thread that you're using a GTX 1060. That's probably underpowered for a high-refresh rate 1440p display, and I wouldn't recommend buying a display like this without stronger hardware.
Facebook
Twitter
Instagram