I haven't shopped for one in several years, so I can't make recommendations of specific makes and models. There are dozens, if not hundreds of them in your $25-$95 price range.
But the basic features most people like are:
- speed,
- average speed,
- top speed,
- distance,
- ride time,
- cadence,
- average cadence, and
- maximum cadence.
Things to look for are:
- display size,
- layout and clarity,
- can you see it with your (polarized) sunglasses,
- can you read it with and without your bi-focals,
- how much or how little you can see on the screen at any given time, and
- how useful or fiddly the button use is.
These last two are highly personal, BTW. What I find fiddly, you may find accceptable, and vice-versa.
For example, Cat-Eye is probably the most popular brand out there. People love 'em. I find them fiddly, obtuse, and difficult to use. Both sides of the argument are right because different people think differently. Don't avoid them because I don't like them, but when shopping, pay attention to which buttons you push, and in what sequence to get to what you want. You may find them perfectly clear, and easy to use and understand.
I prefer wireless since then I don't have wires from the sensor down to the bottom bracket and rear weel cluttering up the bike. There are two types of wireless:
- Digital is the one to have. Digital is interference-free, reliable and accurate.
- Analog is to be avoided. Analog goes nuts near power lines and other radio sources, and cyclists with the same or similar make and model.
Of course, wired is both cheaper and completely immune to such interference. But you have the wires draped all over.
Backlights seem like a nice idea, but in my experience, after dark I'm too focused on the road ahead of me to look at the cyclometer. Plus, in this price range, you're looking at disposable batteries, and backlights eat batteries.
Hope this helps!