I feel like these expensive, GPS-integrated, wireless ones are actually the opposite of what a bike computer should be.
Picrel was $20, takes one battery, and gives speed/distance/time. If you're fancy, then you get the one with a second, wired sensor for cadence. Never needs to leave the handle bars other than to change the battery once in 18 months.
If you need directions, stop and take out your phone. But you don't need your phone on your handlebars.