Opensuse OBS. Tiny bit better because the build environment doesn't allow a network and binaries are not allowed as far as I know. Fedora has a similar thing COPR. Both of these support building packages for other distros as well as appimage, flatpak etc.

With opensuse official packages also use the same infrastructure. It is actually quite fascinating and powerful. (I know a lot less about COPR but I would imagine it would be equally as good. Wezterm switched to that for its packages)

AUR is fast and loose and doesn't do much "handling" by design, so it's hard to find any equivalent repo. But there's always a tradeoff between fresh (nixpkgs unstable, might be the closest) and tested (Debian).

Gentoo

But let's hope we get this solved, like peer review model, vouch, or something

It is very good to be able to find build/install files for everything

SlackBuilds.org is pretty sensible.