I don't know why it took like 4 years to discover this advancement in Nostrology that's incredibly obvious.
Make other relays in the pool race the fastest relay. No complex scoring system or relay manager needed. Just start a very short timeout (eg 200ms) after the first EOSE from any source to allow for other relays to get a word in.
This prioritizes fast relays, as we should. It might even come down to latency of whichever relays are closest to you (a happy accident of this system that promotes geographical distribution).