The 8700K runs hot. I would recommend a dual tower dual fan air cooler like the Cryorig R1 or my fav Noctua NH-D15.
As far as AIO water coolers they typically don't offer any better performance then a good quality air cooler, some are actually worse. However they are far more low profile and with some Mobos the large air coolers can interfere with RAM clearance, though most have taken that into account it the design.