1) In terms of pure boxing skills 2) In terms of excitement Wlad Klitschko vs Sultan Ibragimov (2008) Wlad Klitschko vs David Haye (2011) AJ vs Parker (2018)
Neither fight was entertaining that's right but some boxing purists might like to watch these types of fights
I've only ever been accused of being a "purist" and hell no, nobody liked these fights! Joshua/Parker hands down because of how even I scored it and the tactics being used by Parker to upend the mass expectation.
The Haye fight. Because I hate Haye. Wladimir's one of my favorite boxers of all time. But I ain't gonna lie, many of his bouts are not entertaining to sit and watch start to finish. Ibragimov and Haye among the finest examples of that.