I'd say the Clippers and Nuggets definitely improved the most as title contenders but that is merely because their injured players are presumed to be back.
Accounting for actual off season moves, I'd put Boston ahead of Philly, though behind Atlanta. I'd also put Minnesota ahead of Boston. The future price of Gobert was huge, but the immediate this season impact should be greater for them than Brogdon or Gallinari are for the C's. So I'd have Boston at 3, but with Atlanta and Minnesota ahead of them. I think a guy like Brunson going to NY also could have a greater impact on the Knicks than Boston's moves, but I don't consider the Knicks anywhere near the same level of team so I wouldn't have them high up on the list. Also, to be clear, I don't think Atlanta or Minnesota are better than Boston, just that their moves would have a greater impact on winning.