I would say Lagat and Ryun as 1 and 2, Shorter, KK, Pre, Rupp, Rogers, Scott, Webb and Meb are hard to rank. I would say Rupp is in the top-5, but no higher than that becasue so far his only global championship credential is his Olympic silver medal, which is a real big deal. But, Rupp does not have any WXC stats, he doesn't even have a national cross title, which is weird considering he is the 10K AR holder. He has one national 5K track title and 5-6 10k track titles, but most of the 10K titles when when the top runners were clearly in the 5k. Rupp will likely get the outdoor 3k and 5k ARs and he has a good shoot at another global championship medal...at which point his legacy will be complete as the USA GOAT.
For the women, it is a lot easier:
1. Mary Decker
2. Kim Gallagher
3. Joan Benoit
4. Doris Brown
5. Madeline Manning
6. Regina Jacobs
7. Shalane Flanagan
8. Lynn Jennings
9. Jenny Simpson
10. Denna Kaster