There has been about 150 views on this topic. I suspect you are not getting any recommendations for the liquid cooling side is there are not many here using it. There is also the catch with warranty, does not apply to the Socket 2011, (Thanks Phillpower2,) Where a cooling solution is supplied with a retail CPU, from both AMD and Intel and you choose to install an aftermarket solution and/or OC, any damaged caused will void the warranty, also applied to video cards.
When you get to the top end coolers, there is not a huge difference between air and liquid, downside to air is they can be really big and can prevent you installing tall RAM. Some more reviews.