Two distros that have created an identity for themselves in the Linux-verse are Arch and Gentoo. Both are independently developed and have a steep learning curve, placing them out of the reach of mere mortals. However, the legends who can work them can use them for any purpose. Arch has a lot more derivatives than Gentoo, but both have a strong community. One key distro that was lost in the annals of time was Mandrake Linux, the first true desktop distro. It lives on in the form of two derivatives, Mageia and OpenMandriva, both of which are vying to become its spiritual successor, and use tweaked and updated versions of many of the tools that helped Mandrake become popular with early Linux users.
Just like Ubuntu, which has become a key distro while being based on another, Linux Mint and Pop!_OS are two popular Ubuntu derivatives that have managed to take the fancy of desktop users.