Bulls won six (Including two threepeats) in eight years. They would've won 8 straight had Jordan not retired after 93 for a few years. None of the Bulls Finals trips went to a game 7.
I don't really consider the Spurs a "Dynasty". They won a title in 99. Then it took four years to win their next one (03). Then it was two years (05), and two more years (07), for their next two. They never repeated once. That disqualifies them immediately imo. Great run? Sure. Dynasty? No.
Warriors will be one after they win this year's title. Three straight. Four in five years.