I personally wouldn't use any of them- I'd choose a good air cooler for less cost and very similar performance. However, if you wanted to go this route, I'd say choose H60 or higher. H50's were the original model design and the least reliable and worst performing of all listed above.
Pete: Just installed the H60 system on an AMD 970 mb with a 965 OC to 3800. Very impressed with the easy of installation and how well it cools when running flat out.
I have now replaced the 965 with an 1100T OC to 3800. The H60 Corsair keeps the 6 core cool with 34C Idle for the overall CPU package (cores show 24 C each at idle) and a load CPU temp of 56C (cores 43) running Prime 95. The temps are even lower now that I added a 2nd 120 mm fan to create a push/pull system 21C idle 39C max
Thanks ... I went with a Xigmatek Gaia SD1283 - a big beast and yet very cheap from Newegg.
Dropped my temps from 40c (idle) / 65c (load) to 30c (idle) / 55c (load) and lovely and quiet!
Thanks for all the input!