This is such a tough and subjective question that I was going to stay away from it and just read, but I can't resist jumping in. I'm making a lot of assumptions in my answer, namely I assume we are talking about 'everything' they accomplished as a runner.
Rank: Webb/Ritz/Hall
Why Webb?
1. Webb by a large margin broke one of the most entrenched H.S. records. He did this while having a normal H.S. career in terms of running XC, indoor and outdoor, running relays and frequently doubling and tripling at meets. Webb was also the anchor leg on the DMR HSR.
2. Webb finished a season ranked #1 in the world in one event and #2 in another event.
3. Webb has won 4 national championships.
4. In addition to owning the AR in the mile, he is also on the top-10 list in 800, 3k, 2-mile and just outside of the top-10 in the 5k.
5. According to scoring tables Webb's mile performance ranks higher than any of Ritz or Hall's performances.
6. Just looking at the numbers (not victories), the combination of Webb's performances in 800/1500/5000 would probably put him the top-10 greatest MD/LD runners in the world.
7. Neither of the 3 have had great consistency in their pro career, but when Webb was at the top of his game, he was spectactular.
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Ritz is second becasue he has beaten Hall in all but one of their head to head match ups. The marathon is just one event, Ritz is accomplished in 5 events. If you could adjust for the course and conditions, Ritz would probably have a faster HM PR than Hall. Medaling in Jr XC and the world HM probably does not register with a lot of people, but people who really know the sports, know that those a really big deals.
With all of that said, I can easily see how people would rank them differently...which I could possibily do myself on a different day, for right now I am pretty solid on Webb.