I have $500 for a monitor.
I game competitively so 144hz + is a requirement.
I want 27 inches or larger 1440p and the best colors possible.
No curved displays.
It would be great if the monitor could detect what game i am running through software and automatically change color profiles.
Is this any good? Haven't been able to find good information on its input lag.
Depends. It's different in the sense that it has its own set of issues. The most notorious one is slowish response times for dark shades, which is commonly called "VA smearing". It's not always an issue, but some find it to be pretty annoying when it does happen.
As for the other two, the Dell is a TN monitor, which means that it will have the fastest response times and the narrowest viewing angles (colors will visibly degrade toward the edges of the screen). The Acer sports an IPS-type panel, which makes it somewhat similar to the Nixeus.
From my understanding of the best compromise of what you want in a monitor, both the Nixeus and the Acer are the best options.
I have the Dell.
It's fast.Really fast and works at 155hz.
But since you want color accuracy,it's a TN and you might wanna look at something else.
Colors are a bit faded compared to an IPS,not something disturbing,but noticeable.
Viewing angles however are pretty good.There is also a bit of banding,you won't notice if you don't look for it.
does it have to be 1440p? do you play csgo? if you can manage 1080, I would consider an Asus VG279Q.
from NCX review page:
The Asus VG279Q uses an AUO AHVA panel (marketed as IPS) which provides the best balance between image quality and pixel response times since AHVA panels are free from color evenness and vibrancy reducing gamma shift, and have wider viewing angles than TN and VA panels. Fast AHVA panels (marketed as IPS) like the VG279Q have significantly faster pixel response times than VA panels, and are usually only slightly measure-ably (with an oscilloscope) slower, and barely perceive-ably slower than TN panels.