He wasn't better than Rio.
I reckon he was.
I've always thought Rio was extremely talented but a bit of a bottler. Vidic was the rock back there we needed which is why he became Captain. Rio was never captain material at any point in his career.
We won our first PL title in 4 years in Vidic's first full season and then totally dominated afterwards. Our attack was great in this period also but it was our defence which was truly legendary.
We once went 12 games in the league without conceding a single goal.
Van der Sar played a big part also but I think Vidic was the catalyst. He had that inner drive and determination only the true leaders have.
Overall, I'd say Ferdinand was slightly more talented but Vidic had a lot more to him than just talent.
Both were excellent but Rio gets regularly overrated whereas Vidic gets underrated. It's just the English media's way.
Stam was better than Rio also.