I also have not had any issue with AIO over a number of years, even past what is commonly cited as safe (5 years). This could certainly be an aspect of how quality a unit. At least in times past, many of the AIO were pretty much the same unit, for sure often the same pump, and worked very similarly and reliably.
Air cooled rigs can tend to be a lot noisier but that can depend a lot of what fans, what control type, case fans as well as the type of case. Also, where the case resides in relation to your seating position.
I am not terribly familiar with Gigabyte BIOS, but check on the section where you control your fans for something like "smart fan" or an option like fan tuning. In most cases where you are looking for as quiet as possible with powerful hardware there is going to be a trade off for heat threshold as well.