Of the modern ones Robert Carsen is inventive without being offensive and it's clear that he has a great love for opera, as opposed to (of course) Calixto Bieito who seems more interested in destroying the art form. Holten's work doesn't do it for me at all.

Pountney and the Aldens are fine. Pierre Audi is interesting.

Of the old guard, certainly Jonathan Miller, and I'm content with a Moshinsky or Zeffirelli.