Wired cycle computers are, if fitted correctly, more reliable, cheaper to buy and cheaper to run.
The problem that many folks seem to have with wired comps is not running the cable properly and it ends up damaged as a result. Refer to the manuf.s destructions, take your time and you cant go wrong.
The trouble with wireless is that the wirelessy bit introduces another battery powered component, the transmitter. Another battery to fail and another component to play up as well as a more complex head unit now that it has a receiver in it.