Start with what you need to read
Four digits are enough for hours and minutes; six add constantly visible seconds. A bedside clock also needs the right alarm, snooze behavior, and night brightness. More information is not automatically more useful.
Timekeeping method shapes long-term use
A quartz clock occasionally needs manual correction. A WiFi digital clock can synchronize when a network is available. Before buying, check whether it continues keeping time offline and whether settings survive a restart.
Controls, power, and minimum brightness
Button placement, menu depth, and the quality of the manual determine whether features get used. The lowest brightness matters most in a bedroom; cable length and connector direction matter on a desk.
Common question
Must a WiFi digital clock stay online all the time?
Usually WiFi is mainly for synchronization or setup, but behavior varies by model. Check its manual for offline timekeeping and saved-setting behavior.