That by itself is a very subjective question. It depends on the purpose of your build, and whether you plan to OC your PC. Heck, there are folks that OC their PC on air cooler as well, and there are folks that are on custom water loops just for fun.
I just built two identical spec-ed PC as per my system build to the right, but one is on air, while my own build is on water. Both works just fine as it is, and I recommend both as well, because it boils down to the usage of the PC and whether the end user is comfortable with water running in a computer.