Very unlike the Windows world, you will find relative few Mac users doing 3rd party tools. If any of those vendors say they are #1, ask yourself how many thousands copies it takes to have that title in the Mac world. Not so much.
I'd suggest that Disk Utility that came with your Mac (look in your Utilities folder) is probably everything the typical user is ever likely to use. Having said that, odds are that the typical user won't ever feel the need. Like the above poster says, these sort of apps really aren't needed very often at all.