I have the H50, and I'm very happy with it. The H70 is apparently hardly any different in terms of performance, and a lot bulkier.
a lot of people on here rate the Prolimatech Megahalems, and say it is on par with the H50.

In the cooling market, corsair is known for its superior cooling performance, quiet operations, and ease of use. In order to improve the performance of the Corsair Hydro H50, go through the following Corsair blog.
http://blog.corsair.com/?p=987
Thanks.
To anyone that knows
Can I improve the performance of the H50 with different and/or extra fans ?
What do people mean by "push pull" when talking about water coolers ?
If your going push-pull you will also need some extra screws. I have some spare if you need some, got a bag of 20 odd.