1. Boston Celtics
The gold standard. There's a reason Durant doesn't feel the need to give Jayson Tatum and the Boston Celtics any advice. It's because they don't need any. Obviously as the most recent champion, they're the best team until somebody takes the crown from them or they fail to reach the heights of before.
But looking at this from a bigger picture, and the Celtics have come to embody everything that the Suns are not, and it is the main reason they're the better of the two right now. Whereas the Suns drafted Booker and tried to surround him with star teammates, the Celtics selected both Tatum and Jaylen Brown.
It took some trial and error - including having Irving themselves at one point - but they eventually realized that having two stars and a deeper supporting cast was the way to go. Most other franchises think the same way, and every champion since at least 2019 has been built on a "two stars and the rest" foundation.
The Suns however are stuck in the mode of roster building from over a decade ago, when LeBron James, Dwyane Wade and Chris Bosh came together to win championships with the Miami Heat. Until the Suns can sort out the shallow depth on their roster though, the Celtics and plenty of others are going to remain ahead of them.