I prefer analogue clocks since they tend to be smaller in desk footprint and they are much easier to manually adjust (you need to do 20+ beeps on a digital alarm clock). They also just look kind of neat. I prefer if the clock ran on AA batteries (not AAA, and definitely nothing non-replaceable), and some sort of backlight would be ideal (but a good white/warm one, not a blinding blue/green light!

edit: I have bought two alarm clocks by “Rhythm”, they take a single AA battery each and have cute colours too. Quartz movement, backlight, everything! I also found the Braun BC02 (and BC03, the bigger one), which also uses AA batteries + quartz movement + backlight, but it only came in black or white, at least where I was purchasing it.