It's a matter of perspective, regardless of any personal aesthetic inclinations. It's also a matter of degree. As nonsense pointed out, correctly, a 'Good' air cooler will outperform any aio. Upto a certain point. Air coolers are limited in the amount of cooling potential. Even the biggest and best like the Noctua NH-D15 has limits that can be exceeded by high OC on powerful cpus. But those are more extreme cases or mostly the 2013 boards+. For newer lga1151 from skylake and up you are more likely to run into vcore limits than thermal limits, so a good aircooler is all that's required. On Haswell and older cpus, it's possible to exceed an aircoolers limits and this is where the 240/280mm AIO's take up the slack.
For the most part, the only real noise associated with either is the fans. It's entirely possible to have an air cooler that's miserably loud such as a CM hyper212 at 2k rpm, or an AIO that's extremely quiet such as a nzxt Kraken X61 at 800rpm. Some AIO's are very loud for no other reason than crappy fans, Corsair and Enermax are guilty of that.
Same can be said of custom loops, they do have more failure points, inherent with multiple connections, but because of the sheer volume of thermal absorption potential the chances of overheating are slim if planned halfway correctly.
OC is a hobby, not a necessity. So cooling beyond stock ability is also a hobby requirement, custom loops being the ultimate form of that. Also by far the most expensive and most hands on, requiring periodic maintenance. Aircoolers will work forever requiring nothing more than cleaning, AIO's have a undetermined shelf life (some have ability to renew the coolant so become unlimited) but custom loops require redo of liquid totally every so often as the liquid becomes unusable, contaminated, old.
All 3 have definite bonuses and advantages and all 3 have drawbacks. There's no 'best' or 'ideal' solution only personal preference and needs.