Crawford Spence has had years of build up and back and fourth. Both guys are usually reserved but I think they would bring out the fire in eachother that could lead to an entertaining pre fight build up. Only reason I could see Fury Vs Usyk being bigger is because they're heavyweights.
Spence and Crawford would probably be more interesting for the boxing purists, but bigger? Definitely Usyk/Fury. In both popularity and physical mass
Americans care more about Spence vs Crawford Everyone everywhere else on Earth cares more about Fury vs Usyk
Only Americans might think Spence Crawford is bigger because they have no involvement in the heavyweight clash.
I'd go with Usyk and Fury in terms of talent of the two fights. I thought Porter edged Spence. Thw biggest fight in terms of possible money made? I don't think any fight fight come close to an AJ vs Fury potential fight.