That would all depend on what you want. Do you want a quiet one or can you stand noise? Are you on a budget constraint? What are you OCing?
I ordered a Thermoengine with a Black Delta fan. The others say it is a LOUD fan, but I have 3 120mm HO fans right now. I don't mind noise since I am half deaf anyway ( I crush rocks for a living) The link is http://www.azzo.com
The site I got my fans from is http://www.3dfxcool.com They also have HSF for sale. I am sure the others will have more input than me since I am relatively new at this myself.
The thermoengine with a loud delta fan is the king of the ring.I just ordered a black label delta fan to go with my thermoengine.The intalling of the HSF is a piece of cake cos the clips are not very stiff.Just apply pressure on both sides.EASY