I've used O&O Defrag for years! It was pretty sweet and had some great features. The last one I used was v10 nearly a year ago (the one that started to look lik an Office 2007 app). Since I formatted my system back then I just never reinstalled or purchased the new one.
O&O Defrag also has idle defrag and other automatic modes. It's a comprehensive disk defrag solution.
In my experience with O&O's utilities, Defrag is their best (it feels like they put the most work into it).