Do you plan on high overclock on your I7, and how much do you want to spend. The reason I say this is for a mild oc, there may only be a few degrees diff between a good HSF and the Best, but the "Best" may be considerably more expensive.
Yes there are some that use two fans in a push-pull configuration
Check out the HSF "roundups" or evals and or comparision charts.
You can also check newegg to see what seams to be the most popular, read reviews - just take with a grain of salt.