And that is the base problem with games today. Everyone expects to be 100% the same, but with the old school RPG style games, which FF is based on, certain classes were better at specific jobs and other classes were worse at them.

Tanking content that you are not geared for: Go with a paladin
Tanking content that you are over geared for: Go with a warrior
Tanking content that you are correctly geared for: Pick whatever one you really want to...