I would rank the EC challengers to the Celtics' title pursuit thusly:
1. New York Knicks. They have the best defense in the conference, and get enough scoring from Jalen Brunson and Josh Hart to steal a few games. But Julius Randle is their 2nd leading scorer and leading rebounder, and he's out for the playoffs; and OG Anunoby, their best defensive player, is nursing a sore wrist. If Anunoby can play, the Knicks have a puncher's chance of knocking out the Celtics.
2. Milwaukee Bucks. With Giannis Antetokounmpo and Damian Lillard, the Bucks have the biggest 1-2 punch on offense, and when they're hot, not even the Celtics can keep up. The trick is, can they do it 4 times in a 7-games series? That will depend on their supporting cast. Offensively, they run 9 deep: Giannis and Lillard average 55 points a game, then Khris Middleton, Bobby Portis, Brook Lopez, and Malik Beasley total 52.5 points per game, with Jae Crowder, Pat Connaughton, and Patrick Beverley contributing 5-6 points each. But their defense in mediocre: they allow about 117 points per game, 22nd of 30 NBA teams. They're going to have trouble slowing down the Celtics' offense.
3. Philadelphia 76ers. It all depends on Embiid's health and conditioning. If he can go seven games in a series, he can provide enough offense and defense to carry the team. Tyrese Maxey is a good second option, but after those two they have Tobias Harris, Kelly Oubre, Jr., Buddy Hield, and Kyle Lowry. De'Anthony Melton is out with a back injury and no timetable to return. They just don't seem to have a lot of depth.
4/5. Cleveland Cavaliers/Orlando Magic. These two defense-first teams can slow down the Celtics attack, but don't have enough offense to stay ahead.
6. Indiana Pacers. They have the NBA's highest-scoring offense. They also have the NBA's third-worst scoring defense. Some of is due to the faster pace they play. I'm not sure if that will play well in the playoffs.
7. Miami Heat. They're now the poor man's Cavs. They may not make it out of the play-in bracket.
8/9. Atlanta Hawks/Chicago Bulls. They have losing records. No, just no.