This all depends on the case you'll be using and the maximum cpu cooler height/radiator support.. Yes pumps do fail, but there are built in thermal protection technologies in the processor to ensure they do not over heat to the point of damaging hardware and these failures only seem common because people that have had good experiences with them are too busy using their systems and rarely take the time to leave positive review feedback. There are new Noctua Chromax all black air CPU coolers, however they haven't been released yet and the Deep Cool Assassin III supposedly can out perform the NHD15, however the NHD15 outperforms the Deep Cool Assassin III in acoustics (Not decibel but pitch) however this would not be a deciding factor for myself.
The only caveat to air coolers that size is blocking ram RGB aesthetics and the weight of the air cooler itself. For those reasons I will never go air cooler in a high end system like the one you have because if you're spending that kind of money, spending a little bit more on an AIO shouldn't be the deciding factor. I'd rather mount the AIO to the case and use the preapplied thermal compound on the AIO, resulting in ease of installation and better aesthetics for the money.
My only exception to high end air coolers are my test benches due to having the motherboard horizontal and strictly non RGB builds where there is no glass on the side of the case where aesthetics are not an issue. Don't get me wrong, there are circumstances where high end all black air coolers like the bequiet dark rock pro 4 looks amazing in certain builds.