CCleaner hsa been doing the "Defragment and Vacuum" Firefox and I believe Chrome - since they started using SQLite a few years ago.
CCleaner calls the feature "Compact Databases"
In fact ccleaner does several things better - the ones that I noticed immediately - ccleaner lets you define multiple custom folders (to clean) - Platinum Guard gives you only one.
Also Platinum Guard doesn't let you exclude cookies from certain sites from being cleaned. It is handy to do this when there are sites you regularly visit (like GOTD) and you want to keep those cookies so you don't have to login manually again each time you visit. Also some sites store user settings or preferences in their cookies. Platinum Guard makes you wipe everything or nothing, CCleaner is more flexible - permitting exclusions for certain domains.
Platinum Guard has no mention of cleaning settings for Microsoft Office, Flash, Windows Media Player, Adobe Reader and other privacy related settings like Recently typed URLs.
Be careful of the Platinum Guard "Intensive Computer Clean" - it works like a computer version of "Racial Profiling" - deciding (generalising) that any file with a particular file extension must be rubbish and is ok to delete. Sometimes (Usually?) it is - but not always.
CCleaner is a really tough product to outdo because it has been around for such a long time and is very mature. I really would like to see a quality program that can not only copy the function of CCleaner but be innovative and smarter in how it works. It seems there are hundreds of clones and wannabes but nobody seems to be doing much to move this type of product forward.
That the developer wants to (normally) charge $13.99 for Platinum Guard when CCleaner is free - just makes this more frustrating. Sure I agree that developers need to pay their bills and eat too - but they should realise that starting to develop yet another "file cleaner" is not the best business decision unless there is something that makes their product better than the competition in some way. Otherwise expecting users to pay money for a product that is inferior than freely available products just feels like a swindle. If you want users to pay - they should know what they are getting for their money - make sure you are giving them something that the cheaper alternatives cannot.