I like Sigma and Planet Bike. I tried a Cateye once, but you can't set the odometer on the basic units and that's incredibly basic functionality IMO, so I returned it.
I've also bought $5 units off eBay, and they work OK as well, though the controls were a little confusing and I accidentally reset the unit a couple of times, gave up and bought a Planet Bike.
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Work: the 8 hours that separates bike rides.