We've done Superman variants in strength. Who is the fastest in flight feats. I recall that PC Superboy and Supergirl flew to the Andromeda galaxy for a picnic and back to Earth in a few hours. We recall the famous Supes chasing an unconscious Supergirl so fast to threaten the universe. Spectre caught up to him (that's a speed feat, ignored a punch and sneered at a superspeed attempt to dodge around him). Supes didn't need oxygen in those days. As an aside, how to they see where they are going as visible light is years and years and even million years out of date.
So - with all the versions - who's fastest. Superman 1000000 with a GL ring is clearly intergalactic speed level. Who else?