EDIT: Any advice on water cooling units? If I go with the 2500k cpu, I'll want to overclock, and certainly don't want to fry it.
There's a few sealed and self-contained water cooling units out there. I know Corsair has a few variants, namely the H50, H70 and H100 for various prices. (though based on a quick look it appears the newer H70 has basically replaced the H50 for the same price)
However if you don't want to mess with water than the CoolerMaster Hyper-212 Plus has good reviews (plus it's not super thick like some either) and if noise turns out to be an issue you can replace the fan easy enough.
In general what I hear from the reviewers and experts is a good air system can just about equal a water system and be less of a hassle.
Granted installing any of those is going to be interesting in different ways. Water for dealing with the hoses and air for dealing with the large tower and back plate together. You'll want to install the cooler before the motherboard goes in unless you got a case with a door on the motherboard plate.