1. Rudisha (2 World Records, Olympic Gold, World Championship Gold, 1:40.91 PR)
2. Snell (World record, 2x Olympic Gold)
3. Kipeter (3 World Records, Indoor World Record/World championships, Olympic Silver, Bronze, 3x world championships)
4. Coe (2 World Records, 2x Olympic Silver)
5. Cruz (Olympic Gold, Olympic silver, 1:41.77 PR)
Depends if you value World records more than Olympic Golds, and how much you value world championships, how much silvers and bronzes are worth, etc.
If you value amount of time holding the world record, or how much the record was lowered by...
If you value Olympic Golds most...
If you value # of times breaking the world record, or world championships, or indoor at all...
If you value simply who covered 800m the fastest of all time...
Cruz could be anywhere from #2-5 depending on what matters most, if he had ran .05 faster he would have Oly Gold, Silver, and World record for 10+ years, and there is some doubt about the florence time from Coe anyway.