This is a good post, but in terms of comparing them, Hassan is just on a different level. She's more than half a minute faster in the 10k, even though that was perhaps Dibaba's best event (and not necessarily Hassan's). In addition, her championship performances, like the 3:59 close in the 2019 10k or the triple in 2021, are well, well beyond what Dibaba could have done at her peak.
Say you're comparing two NCAA cross country runners. Runner A is a historic D3 stud, winning the NCAA title in all four years and never losing a race. Runner B is a D1 stud, winning two NCAA titles, but being injured, inconsistent, or just bad the other two years. I think nearly everyone would say the Runner B was greater, just because it's a totally different level of competition. There's no real question that if the two raced at their respective peaks, Runner B would win. It's plausible that B could have done what A did, training less to be more consistent and winning over lesser (but still excellent) competition; but inconceivable that A could have done what B did.
This comparison feels facile, but the chasm between Hassan's level and Dibaba's is immense (or Hassan's and almost anyone's), close to half as big as the Runner B -> Runner A gap. How can we compare the two, given that in every one of Dibaba's best performances we can be pretty confident that the Hassan of the past few years could have beaten her?