Both products are doing it job and improvements are obvious each time they released a new build or version.

Other than the price (CCleaner $0 while Window Washer is not freeware), CCleaner has its web forums.

Window Washer let you password-protect, schedule a wash. Window Washer has this new feature that will total erase the system (format) when you want to. Then you can have your log available. CCleaner don't have those.

I'm also using another freeware cleaner - It is "Internet Window Washer" by eusing.com. It has extra feature like scheduling when it will clean/wash, auto-start with Windows, password-protect then it will verify the password when running, Boss key etc... The features of Internet Window Washer is almost similar to Window Washer by Webroot

CCleaner and Internet Window Washer are light in resources.

Window Washer, CCleaner and Internet Window Washer are all doing what it ask to do.