I'm not 100% sure if there is an official repo for arch.
But the latest stable version of sugar is 0.106.1 and the latest unstable is 0.107.0. I would recommend 0.107.0 if you have a newer Gtk+ version, as it fixes some more regressions.
Sugar in the AUR is 0.106.1, which is pretty recent.
I don't know what version of sugar [city] has.