Onyx interface is very clean and usable. Onyx lets you get deep within the Unix structure. Now, this is good if you really know what you are doing, but if not, you can really mess up your system. Sometimes, the lesser you know, the better it is. Onyx is remarkably good value for a free software. But the EULA clearly states that, should anything go wrong in using it, you cannot hold anyone but yourself responsible. For a newbie int the mac world, this is definitely not reassuring.
CleanMyMac by MacPaw is one of the nicest ‘looking’ Mac apps currently available. But, like the name says, that is exactly what it does – Cleans out your Mac. It also allows you to uninstall apps efficiently, removing all traces and preference files, and also erase files permanently. Overall, it is a really nice app for the functions it states to perform.
MacKeeper by Zeobit is the best of the lot. It does all of the above, and a whole lot more, very efficiently. It packs in a GUI which is very similar to the Mac OS X finder layout. This makes it very intuitive to get around. Every function also has a detailed video tutorial which clearly explains everything you need to know. The major advantage that MacKeeper has, over the others, is that they have a 24/7 support team to assist you, should you face any difficulties.