As many videos has already pointed out that ryzen 3000 series has almost at peak performance out of the box due to Precision Boost 2, I think the stock cooler that came with the Ryzen 3600 will do just fine.
I have a Corsair H215 pro pro on my Ryzen 3600 and I regret getting that cooler I should have gone with the stock cooler or a nice aftermarket air-cooler (for aesthetics) but other than that no performance gain to be had unless you would go to sub-zero OC.
if I were to choose between Dark Rock Slim or AIO, I would pick Dark Rock as AIO has a pump which another point of failure.