Lets bet on this. You state how long you think before it will break/start buzzing. I'll put £20 on this. As long as it's a reasonable time you'd expect the AIO to last, obviously if you say something like 10 years then that's not happening.
Corsair H105 or H100i, not sure yet. Yes you can change the part that breaks in a custom but for me an AIO is just less hassle. Don't have time to be fiddling with a custom loop and making sure it works right. With an AIO I'll just unbox it and mount it. If it doesn't work out the box, send it back.