Breckenridge has the best jumps, and is extremely well maintained. But can be horrible in the busy season. Id say its the best, as long as you catch is on a good day. (right season, weather, crowds ect.)
Mammoth has a better early season, better late season, better park weather, and is generally less busy, and arguably has the best parks in the world. I would say its more consistently good, but isnt as good as breck on a perfect day