Sunni scholars strongly affirm the precedence of Abū Bakr and ʿUmar. Early authorities also transmitted positions preferring ʿUthmān, preferring ʿAlī, or withholding a final comparison between them.
Such differences do not amount to insulting either Companion or invalidating his caliphate. Different scholars weighed particular merits differently; some acknowledged both men’s greatness and abstained from a decisive comparison.
The issue is one of relative ranking, not a denial of either person’s faith or companionship.