Well, I'd like the computer to show ride time, distance, speed and cadence at the very least - if you are training, then you'll also want HR. Altitude and/or gradient are also nice to have.

Another factor to consider is how much info you can see at once, without having to scroll through various displays. I just got me an Edge 500 and I am loving the fact that my main display can show all 7 fields I like to track at the same time.

V.