What you'll often find with these kinds of discussions is that people tend to recommend what they have and avoid recommending what they don't have. Therefore I'll avoid recommending a particular computer and just point out that the "A-brand" manufacturers all have computers in their product line and that at this particular point in time they are all perfectly good.
There are a variety of inexpensive and robust options within that range. You'll certainly be able to find something that suits you.
That's the official line. Now for the unofficial line: As for myself, I've owned a few computers but the one I dive with most is an (aging) Suunto Vytec. Suunto's menus suck balls, in my opinion, but their computers are highly reliable and their deco model strikes a nice compromise between bubble theory and Haldane. (in fact, when they first thought of this we used to call it "bubble wrapped Haldane").
Other computers, like the Mares, are much more "bubble" oriented, which gives different ascent profiles (deep stops) as opposed to the more traditional computers. There is some good evidence to suggest that bubble models have some advantages but the implementation is essential. A poorly implemented bubble model is dangerous. A well implemented one can enhance your safety. I don't know the specifics of the Mares (or the Suunto tek) ones but the impression I get from the ascent profiles they prescribe is that they are pretty conservative.
I'm not familiar with other manufacturer's offerings. I think that I spend enough time online that if there were problems with them that I would have heard about it. I haven't. You'll have to dig into the details of those particular products yourself.
Hope that helps.
R..
