That is subjective.

Any OS that lacks any notion of security is inferior to those that don't.
Any OS that needs a dozen patches just to be usable is inferior to those that don't.
Any OS that lacks a global copy&paste is inferior to those that don't.
Any OS that lacks a good PIM support is inferior to those that don't.
Any OS that has a handful of apps in its store is inferior to those that have thousands.
Any OS that has an SMS application without a character counter and that can't create a contact from an incoming message is inferior to those that don't.
Any OS without a <choose your favourite chat/social app/integration> is inferior to those with those features.

Do I need to continue?