it depends. if u're willing to pour a bunch of time into learning i'd recommend nixos, i love it. if you want something familiar but new, try artix, it's arch with no systemd, you can choose your own init system. if you want experimental low level stuff there's void linux with a custom libc called musl, not great for daily driving but fun to try out. honorable mention to gentoo and lfs. and if you just wan to try a new user experience, just switch your de/wm. niri is an interesting new one i've heard good stuff about.