depends on what you need. I needed the "full" hardware (1.5Ghz, 1GB RAM) to use all apps/functions, wanted an OLED screen and needed a lot of space. I mean, really much. So I got an 820 instead of the 920, since it has expandable memory, but the same hardware concerning speed except for the camera and hardware. Additionally, I love OLED screens, and 4.3" was perfect for me.
If I had the same decision now, it'd be a hard time to decide between 925 from Vodafone with 32GB or the 820, but I think it'd still be the 820, thanks to its size and the microSD slot. atm I'm having 55GB of music ^^