I'm using it as my main OS. I have it installed on 4 machines: a RK3288 SBC, a RK3588 desktop, a x86-64 desktop and a x86-64 laptop. Main incentive for me is customization.

- It makes it very very easy to patch any package before they're installed - just put the patches in /etc/portage/patches/<pkg name>/, and that includes the kernel too.

- I can exclude package features that I don't like. For example, my Firefox doesn't try/offer to turn on the wifi.

- I can also exclude entire packages that I don't like, because the entire dependency chains can be eliminated by disabling USE flags. For example, none of my systems have systemd or dbus. Since last year I don't even have openrc anymore (the other Gentoo service manager). One of them doesn't even have udev. I tweaked it so much, I'm not even sure I can still call it Gentoo.