Price: It's free which means you can freely install most distros on all the hardware you want
Versatility: It's versatile as all hell. From intel-32 and amd64 to various ARM platforms and even somewhat obscure things like risc-v
Resource consumption: being able to have a fully loaded and sexy desktop with 0.2% cpu and 125mb of ram on an i3 system is fantastic
Security and stability: due to the open source nature of the beast it's great to be able to audit your own operating system and contribute fixes quickly and cleanly.