I've used AppCleaner, MalwareBytes, OmniDiskSweeper, and Onyx with good luck for quite a while (Onyx I've used going back to Snow Leopard). The only other cleaning/repair/utility Apps I use which are paid is iStatMenus (which provides the status of numerous system functions), DriveDX (which checks for failing hard drives [and some flash drives if they have SSD controllers in them]), and Disk Warrior (which repairs damaged directories that macOS itself is unable to repair - but an APFS version is yet to be released.)