Joshua knocked out an ATG in his 19th fight. For their 19th fight, Lewis,Tyson,Ali fought Levi Billiups, Steve Zouski and Henry Cooper. I believe Ali struggled with Cooper too? I couldn't quite remember that fight. I'm not saying Joshua is better than those guys but I'm just saying at this stage of their careers, Joshua is ahead. If he fights Fury, he will be fighting another ATG all before his 30th fight and possibly even knock out Fury.
Fury is an ATG since he beat Wladimir who's also an ATG who lost to Joshua.