Be careful, you'll see the H50 and H70 get a lot of criticism here. I however have had good results with it. It all depends on how you mount it, where you mount it and what fans you use.
I had an H50 and moved to an H70 when I sold my older rig, though I kept the fans I purchased separately -- Ultra Kaze 3000's. They move a ton of air.
With my sig rig overclocked to 4.6GHz @ 1.43v, I idle at 24c-28c and full load after an hour of prime is right at high 50s to low 60s depending on slight fluctuations in ambient temperature (which is usually around ~74F).
When you add in the cost of good fans for a push pull, it ends up being as much or more than high end air coolers that come close to or meet the H50. If the absolute coolest temps are what you see, a Noctua NH-14 may be your best bet. But remember, that cooler is massive and comes with two fans (you can add a third). Even if you don't have tall heatsinks or other clearance issues, you won't see much of anything except metal and fans.
I like to look at the internals of my computer through the window on my CoolerMaster storm scout. So I took that into consideration. If you don't have a window or don't want care about seeing the hardware, then get the Noctua.
As for those recommending a RASA -- I'm looking at that as my next move.