Resolution and pixel density
A 27-inch 1440p monitor and a 27-inch 4K monitor are different products. Higher resolution gives sharper text but needs more GPU power for games.
Panel type and viewing angle
IPS, VA and OLED differ in contrast, response time and viewing angle. Choose for the work you do, not only for the refresh rate.
Ergonomics
Height adjustment, tilt, swivel and VESA mounting decide whether the monitor is comfortable for long sessions. A cheap stand can cost more in neck strain.
Ports and charging
Check HDMI, DisplayPort, USB-C power delivery and the number of downstream USB ports. A USB-C dock can replace a separate hub.
Calibration and warranty
Colour accuracy matters for photo and video work. Check the factory calibration, the warranty and the dead-pixel policy.