I'm still unclear whether you want something that will calculate decompression info (computer) or just something that will give you depth/time info. (bottom timer/watch w/depth guage)
If you want a computer, I'd suggest a wrist model that has a very easy to read screen and is not too expensive. You might consider the different algorithms, decide which one you think is right for, keeping in mind that none are proven safer than any other. I'd also avoid unnecessary features like air integration, "buddy check", and probably stay away from the smallest ones as well.
In single tank rec diving, computers really don't need to do much, and don't forget that decompression theories are just that; theories. Avoiding DCS involves many factors that the computer has nothing to do with.