The only real choices are the NZXT Kraken and the Corsair H100i Pro. I would never recommend the NZXT cooler though because of the terrible CAM software.
AIO cooling is largely about the fans. The pumps are almost all Asetek. The radiators are all pretty much the same - Aluminum and 27mm thick. I never stick with stock fans for my AIOs (I have 10 Corsairs at the moment). All of them have been replaced with Noctua fans.
So, if you don't want the hassle of replacing new fans, then as you're looking at coolers look at the fans specs: Static Pressure and Air Flow. Generally speaking higher is better (I'm sure an expert will chime in there and say I'm generalizing - which is true - there is a lot more to fans than just static pressure and air flow).
Keep in mind too - Cooling performance is linked to noise level. Less noise - less cooling.
AIO cooler reviews are rarely apples for apples comparisons, so take them with a grain of salt. But here's a few links...
https://www.tomshardware.com/reviews/best-cpu-coolers,4181-2.html
https://www.anandtech.com/tag/liquid-cooling
https://www.pcgamesn.com/best-liquid-cooler
https://www.pcgamer.com/au/best-cpu-coolers/
https://www.anandtech.com/show/7738/closed-loop-aio-liquid-coolers