Best movie trilogy?

[HoloDust]

Probably not all of them the best, by certainly my favourites:

Dollars trilogy (A Fistful of Dollars; For a Few Dollars More; The Good, the Bad and the Ugly)
Mad Max (Gibson's)
The Godfather (though 3rd was quite weak)
Back to the Future
Before (Sunrise, Sunset, Midnight)
Austin Powers