I've been using the Sigma 1606L. It's been a fine computer. It has an optional cadence (included). Can track two different bikes (additional harness not included). And it has a light. I don't think I've actually used the light though. The manual says to use it sparingly as it uses more power. I cannot compare it to others though because it's the first one I've used.
Ooh. I should add, one of my favorite features of this computer is it's stopwatch. I use that to time my oatmeal and pasta while touring. (I don't wear a watch!)
-Cota