Links (USA):
$450: 27", IPS, 2560x1440...
http://pcpartpicker.com/part/asus-monitor-pb278q
$130: 22", IPS, 1920x1080...
http://pcpartpicker.com/part/aoc-monitor-i2267fw
$160: 24", TN, 1920x1080, 2ms response time (less ghosting than above IPS but possibly not as good viewing angles)
http://pcpartpicker.com/part/asus-monitor-vs247hp
$450: 24", TN, 1920x1080, 144Hz with GSYNC!
*Not recommended due to price. GSYNC is amazing but personally I'd hold off for prices to drop. Another year and perhaps 2560x1440 will be $500 with GSYNC and 120Hz IPS?
$800: 27", 2560x1440... (Asus ROG Swift):
http://pcpartpicker.com/part/asus-monitor-90lm00u0b01370
$270: 24", 1920x1080, TN, 144Hz, 2ms
http://pcpartpicker.com/part/asus-monitor-vg248qe
SUMMARY:
Again, it comes down to budget. I can say while 144Hz allows for higher frame rates (up to 144FPS viewable) you need a bit of extra knowledge or you can have issues with VSYNC.
If you use VSYNC (to avoid screen tearing which is quite bad in some games) you get STUTTER if you can't output a high enough frame rate (144FPS or higher for 144Hz).
For many games the ideal solution if you want VSYNC is to force on the "HALF Adaptive VSYNC" setting on a per game basis. For example, let's say you get an average of 100FPS with occasional dips to 60FPS. Withe the "Half AV" method forced the game will synch and cap to 72FPS as long as the PC can output 72FPS but auto disable VSYNC for those times you fall below this.
*When you use the Adaptive VSYNC method and fall below the target then VSYNC is simply turned off automatically. That brings back screen tearing but avoids the STUTTER which can be very annoying due to the synch mis-match between PC output and monitor refresh rate.