My take:
925:
Metal build, comes in shades of gray (still looks slick)
slightly improved camera
slimmer and lighter
AMOLED display (can't choose)
Qi requires external shell (potential sticking point for me)
920:
more memory (32 GB 925 is rare)
Qi built-in (I use wireless charging a lot)
LCD display, I like it, although I wouldn't be able to choose between the two techs.
colorful polycarbonate/plastic housing
you can't really bother with the 920 being old, because the two phones are practically identical under-the-hood.
I personally chose the 920.