Corsair A70 owner here. Really happy with it, bought it for about $45 back in November. It felt good holding it in my hands and was a very easy install on my MSI P55-CD3 motherboard - which was important to me because it was my first time installing an aftermarket HSF. And I really like the mechanism for mounting the two included fans in a push-pull configuration. It really feels like one, cohesive unit.
I was also confused about what direction to go: A70 for $45, Thermaltake Frio for $60, TRUE or Prolimatech Megahalems (the latter two were running $75+ around the time I ordered). Ultimately it all come down to price.
Here's a quick and dirty screenshot I took a few days ago for a friend. Not a very scientific test since I only had Prime95 running for a couple of minutes but that's where it tops out (mid-70s). Not bad for a 4GHz i5 750 in a budget Cooler Master 590 case (with only one 120mm exhaust) on a warm day with no air-conditioning. And while under regular loads (like playing Crysis, GTA IV etc.) it's around the late 50s to early 60s. Can't really give an accurate number because honestly, I never pay much attention to it.