I didn't use to enjoy wearing sandals very much - they were cheap, became super uncomfortable as the foam wore down, and were generally uncomfortable.
Reef was always recommended by friends (and the girlfriend) as being reputably the most comfortable sandals out there.
I finally decided to try on a few pairs after a particularly arduous day of shopping with the gf, and after going through 6-7 different styles of Reefs, I found the Slap II.

The main difference between the Slap II and the other sandals to me personally was the sponginess of the foam. Each step felt like I was stepping on firm, yet gently yielding toffee. My aching ankles sighed in relief, and I immediately switched on my phone and ordered through Amazon.

I now wear these out anywhere I can, as they're extremely comfortable. And while they cost more expensive than all my previous sandals combined, keeping my ankles happy is a price I'm willing to pay several times over.

EDIT DEC 11/'12: Still going strong! I am using them often in the Philippines and they are still incredibly comfortable. Long duration walks and outings still can get slightly uncomfortable though, especially around the thong area.