I have a Thermalright 120-Ultra eXtreme 1366 with a Sythe fan. It does a great job. I'm running at 4.0GHz on my i7 920 D0. The case also helps with airflow. My PSU is bottom mounted and I have a blowout fan. You can fell the warm air coming out of the top. The case makes a diff. I sit about 55C on the hottest core on idle. I use OCCT for my testing and temps.
Other air coolers I like and have friends who use are the Cooler Master V8 and the XIGMATEK Dark Knight-S1283V. The XIGMATEK is the cheapest of this 3 and is really popular. The Thermalright is the most expensive, I only have it because a buddy gave it to me as he went the high end water route. The Cooler Master V8 looks awesome and works great.