I'd imagine that Jounin would be higher in rank that ANBU since they can boss them around and they don't seem to be getting knocked off like flies.

I think that being an ANBU isn't that big but being a captain of it is the big deal Kakashi and Itachi were both ANBU captains and they certainly don't have to worry about being dropped.

ANBU are sort of like the special hit squads while the jounin are like the higher-ups who run em as ANBU seem to be sent out all the time while Jounin are only sent out on really important things whenever they're not training new genins.