Learn Spanish (Latin America): ¿Ella es sociable? O, mejor dicho, ¿es hipócrita? - Is she sociable? Or rather, is she hypocritical?

Mejor dicho translates literally to 'better said', but in English we usually translate it as 'or rather'. It is a reformulation marker. In this sentence, the speaker uses it to instantly correct or upgrade their own previous word choice (sociable) to a more accurate or blunt one (hipócrita).

Could I use más bien instead of mejor dicho here?

You could, but it changes the flavor slightly. Mejor dicho specifically corrects the exact words you just used. Más bien means something closer to 'rather' or 'actually', and is more often used to contradict a false assumption. Here, mejor dicho is the most natural fit because the speaker is actively catching themselves and replacing their own label.

If we were talking about a man, would it be hipócrito?

No, it would still be hipócrita. Adjectives ending in -ista and some ending in -ita or -ta (like hipócrita, idiota, egoísta) are invariable, meaning they stay the same for both masculine and feminine subjects. You would just change the pronoun, for example: ¿Él es hipócrita?

Why is the pronoun ella used in the first question but dropped in the second?