Ease of servicing brifters
There was a questionnaire on Bikeforums on this topic and here you can see the results: Brifters - how reliable are they?
39 people gave their votes and obviously for most people brifters did not break at all.

The second question is about working optimally. To be honest I am yet to see a brifter which does not work optimally. Brifters have very little to no setting up, so they either work or don't work, no middle line there.
Campagnolo brifters are known to be easily serviceable (assuming you have the parts), but Shimano are serviceable to some extent as well.