Buying monitors

use RTINGS.com, they have measured data for hundreds of monitors and they tend to explain the more technical bits.

other websites with harder to parse info:

• LesNumeriques (French)
• TFT Central

if you care about gaming:

• Look for decent refresh rate (120hz and up)
• Look for Variable Refresh Rate
  • Freesync is almost everywhere in gaming monitors, G-SYNC is a nice premium
• Response Time and Input Lag should be low (less than 10ms would be nice)

if you care about good picture quality:

• Look for NATIVE contrast ratio
  • at least 1000:1, 1500:1 or up recommended
• Look for the Pre-calibration Color dE
  • anything more than 5 is garbage, less than 2 is great, less than 1 is pro-grade
• (Extra) Look for HDR and color depth (windows support for 10bits kinda sucks tho)

in any case:

• Make sure it's Flicker-free (no PWM in backlight)
• VESA (Wall Mount) is a nice extra if you want to get monitor arms in the future
• Always shop for the exact model number, monitor brands pull stupid stunts where different sizes or model names are completely different.