So I am putting the finishing touches on my dream touring bike (pics to come) and I know 0 about cycling computers, I think wireless is a must, besides that.... I really don't have clue. I have access to QBP so if it is a brand they carry that's a plus.
If you have no experience with cycling computers, then there are really only two things to look for:
- reliability [which generally means wired with heavier duty wires than some come with]
Simplicity means finding something with relatively few functions. Any function you don't plan to use is extra clutter in the user interface. The computer I got last year is long on durability but I managed to change the language to French, and without going to the user manual I have no idea how to change it back.
1) Speed [they all have it]
2) Trip distance [reset it every morning or at key locations on the map]
3) Trip time [just how long have you been in the saddle today?]
The rest is optional:
4) Odometer [hard to find one without - can tell you how long since you replaced a chain if you keep records]
5) Cadence [if you want to pay attention to it]
6) Average speed
What you probably DON'T want is the ability to switch it between bikes. That increases the number of functions it has to manage, and the price.
And yes, wireless means twice as many batteries, and they sometimes don't register even with good batteries, esp. in cold weather or if there's RF interference about, which can include phones, power lines, dynamo hubs, ...
And the weight of the extra battery and circuitry in the sending unit is more than the weight of the wire you've saved.
The only reason I can see for going wireless is if you have a coupled bike and would need to take the computer wire harness off to pack the bike in its case.