There are basically 3 kinds of water cooling; custom loop, AIO that are not CLC and AIO that are CLC. CLC is a sub-group of AIO coolers. CLCs are all factory sealed with no provision to service and repair. The only thing you change is their fans. Asetek has the US patent on the concept of pump on waterblock in sealed loop system, so any company selling CLCs with pump on waterblock has had Asetek make it for them or is paying royalties to Asetek to be allowed to make their CLC. They all have aluminum radiators, no fittings, no fill port and a pump with about the same rate of flow as a healthy adult can pee after a few pints (up to 40-63L/h) .. by comparison arguable the most popular custom loop pump the D5 flows up to 1500L/h. Enermax Liqtech TR4 pump is rated 450L/h, but Enermax has had serious problems with some owners having had 2 units replaced because of pump problems .. so not a good unit to be considering either.
AIOs that are not CLC are ones like Swiftech H series which they make and sell .. or ones made by Alphacool makes like their own Eisbaer, Fractal Design Celcius and be quiet! Silent Loop. I won't buy Alphacool brand because of reports by owners with defective product who were having serious problems with Alphacool getting problem resolved. Maybe they have got better, I don't know. I will buy Silent Loop because I know they have good customer support if I need it. Same with Fractal Design.
As for air cooling, a good air cooler in a system with case airflow setup to match CPU and GPU air cooler airflow needs will run cool and quiet with same loads as CLCs can cool .. and do it with virtually no potential problems or failures and generally at much lower prices. They only thing that can fail in an air cooled system is fans .. easily replaced at low cost if one ever does fail .. and system is usable even with a fan not working or any fan can be used until new fan is in hand. With a CLC if it fails it's almost always the pump and you have no cooling until a new cooler is installed, so no computer to use and have to buy a new cooler costing several times more than a fan .. and that is if you have a fan go bad. I haven't had a fan fail me in .. I can't remember the last time I had a fan go bad .. it's been at least 10 years and I have 5 systems running here and have built hundreds.
CLCs cooling low wattage will last several years, but I have followed up talking to users who overclock to high wattage / heat and their is a direct correlation of CLC cooing high wattage having much shorter life than ones in low wattage use. CLC users with extreme overclocks often have problems after 1.5-2 years of use .. and when they change to a top tier air cooler end up with same temps and lower noise levels.
Using CLC or air cooling is your choice. What I've posted is in the hopes you will learn and understand why many of us will not use CLCs .. and also how many who started out using CLC changed to air cooling and are amazed at how much quieter their systems are .. at same and often lower temps.