I'm very satisfied with my Garmin Edge 810, but it is overkill if you do not want GPS, maps etc. Since Garmin released the 510/810 series this year you might be able to find really good prices for a Garmin Edge 500.
Cateye makes some good bike computers are low prices. Wireless computers are far easier to install and start around $50. Wired computers can be a pain to install, but they go as low as $20ish.
Bell offers a bike computer for 20 bucks that does all that. Has a wire, which I thought I would have issue with but I don't, doesn't ruin my bike aestetic at all. Went to my local bike shop and its the one all the gear-heads there steered me to. They said they'd be happy to sell me one for a hundred and up, but only if I wanted to buy it. If its good enough for them, (and these cats RIDE) then I was fine with it. I asked about wireless and they actually said that your home Wi-Fi can interfere with the computer. Buy local from your local shop and they'll slap it on in 5 minutes.
An oft overlooked issue with wireless computers is RF interfearance. Not home or coffeeshop wi-fi, but things like traffic signal detector wires, high voltage transmission lines, home radio enthusiasts antennae, radar, under ground power lines, etc. I have a couple cheap wireless computers on different bikes and have noticed that while riding it will just go blank, or black out all digits, sometimes even say my speed is close to supersonic! I know the exact areas in town (and the farm lands) here that cause this so I don't pay much attention. I have never had it erase my memory or do anything other than the screwy little things I mentioned, but it does throw off your average speed for moving time though.
The Cat Eye ones have always treated me very well. A couple well placed zip ties and care taken with the slack wire you will never see it. Plus Cat Eye has all their manuals, old and new, available for download right off their site for free. So go buy an old one for $10 and get thr manual and you're set!
I have the Sigma BC16.12. The features I use most often are speed, trip distance, and cadence. Cadence is really important for proper training. It is all wireless, was easy to install, and works really well. I like it a lot. I paid about $95 for it.
I really like my Garmin Edge 200. No sensors, just GPS.
That said, if you have a smartphone, get an APP to do it for you via GPS. Free or low cost. My Edge 200 was $150, but I like that It can be moved from bike to bike to bike in 30 seconds tops.