Best system utilities program

Macs really just don't need the same amount of maintenance attention that PCs seem to. I personally don't bother deleting caches or history in browsers. Caches clean themselves out periodically and are actually there for a reason - they speed things along for you. In Safari, you can delete the history from the History menu.

As for apps, a few files may be left behind but they're tiny and do not affect your system in any other way. An app will generally leave a preference file behind which contains all your custom settings for the app. These can be found in the Preferences folder under your user account's Library. Unlike Windows, there's not all that much point in deleting these files.