Just a quick look on all the teams so far.
Mavs: LeBron - Ray Allen
Raps: KG - David Robinson
Jazz: Shaq - Jason Kidd
Nuggets: Duncan - Gary Payton
Clips: Steph - Grant Hill
Sixers: Kawhi - Klay Thompson
Celtics: Durant - Nash
Bucks: Giannis - Alonzo Mourning
Lakers: Kobe - Chris Webber
Rockets: Wade - Harden
Pacers: Dirk - Embiid
Thunder: Pierce - Paul George
Heat: Chris Paul - Dwight Howard
Nets: McGrady - Anthony Davis
There are plenty of interesting duos. Not sure which one is the best to be honest.
Jazz, Nuggets, and Celtics seem like the 3 front runners to me. Thought all 3 took BPA (with great value) in the first round and got quality value, if not BPA, from their 2nd round picks. They all still have plenty of time to mess it up though.
My favorite duos would be Shaq-Kidd, Duncan-Payton and Kawhi-Klay (in random order).
Imo, Shaq and Kidd would form the best pick n roll duo of all time. Even better than Stockton and Malone. All this team needs now is 3 deadly shooters.
Love Duncan and Payton. Fwiw, Gary Payton is the only player in NBA history to lead the league in three pointers and assists in the same year, doing so in 2000. Best trash talker of all time as well.

Was hoping to draft him with my 3rd round pick. Oh well.
Kawhi and Klay is probably the easiest duo to build around. Both of them are 2-way players who don't need the ball in their hands on offense in order to maximize their effectiveness.
The Celts have Nash's defense to deal with.
My problem with Nash (besides his defense) is that he mostly had one speed: Full speed.
Up-tempo basketball works great during the regular season. Not so much during the post season. Rule of thumb is that the game slows down come playoff time. You gotta be able to adjust. If you ask me, this is the reason the Suns failed to make the
edit WCF NBA Finals under D'Antoni. Btw, the same goes for the current Rockets team as well.