This is the first computer that I have build and I am still trying to sift through all the information. I know the differences between TN and IPS panels. I am looking for a 24in or possibly a 27in, if the price is right. Is 1920 x 1080 enough for a 27in monitor, or do I need to have a higher resolution? I plan on playing a few fps games, but I don't want to make an unreasonable compromise when it comes to how games look. From what I understand display port is the best for connection. I have a MSI R9 270x graphics card. Budget is about $150, but I don't mind waiting a little if there a a good monitor between $150 and $200. Right now I only have a super old Dell monitor to drag me along until I buy a new one.
If you don't mind a glossy screen I would so for a Dell S2240M or S2340M. I would keep it under 23in @1080p. I find that larger then that the lack of pixel density starts to get noticeable. The Asus VS239H-P is a good one for matte screen ips. Stick with IPS screens unless you are going to get a 144hz monitor.