If I'm actually starting a franchise from scratch? Like an expansion team? I'm not calling any of the top guys in the league. Your team is going to suck donkey dick for several years regardless of who the coach is. You need someone who is secure enough to take a bunch of L's while developing young talent and building a culture. Look back at every expansion team or rebuilding job. The coach almost never survives to see it on the other side. Pop is perfect for the Spurs right now because he has no pressure to win to save his job.
Who the best coach in the league right now is, is a different question.
The usual suspects... Spoelstra, Kerr, Carlisle. I like Ty Lue as a tactician in a 7 game series, but I do think he can grate on people. There are also some people who don't like the way he did David Blatt in Cleveland.
I know Bud is getting killed right now and he's probably going to get shitcanned, but his overall record is stellar. People forget that he won 60 games in Atlanta and took them to the ECF before they tore down the roster. In his first year in Milwaukee, they went from 44 wins to 60 (which might say more about Jason Kidd than Bud). He leaves a lot to be desired during the playoffs (to be kind), but there aren't many guys with a better regular season resume.
Everybody loves Nick Nurse, but the only person to get more mileage out of the Raptors championship than Nurse is Kawhi Leonard. Nurse is living off that shit. The Raptors are 116-120 in the last three seasons with two playoff game wins with a roster that should be better than that. I do think he is a pretty good coach, though.
I think Mike Malone in Denver is pretty good. Steve Clifford in Charlotte has always gotten the most out of his talent. I think Darvin Ham has done a really nice job year 1 in LA. Thibs is a weird dude but he's certainly got the Knicks playing at a high level. I like Willie Green in New Orleans. He gets that team to play hard, no matter what.
I think Doc Rivers is the most overrated coach in the league. Not a fan of Monty Williams, at all. Nor Chris Finch. Nor Jason Kidd. Mike Brown had a magical year in Sacramento, but I can't forget how bad he was in Cleveland. I'd like to see what Quin Snyder does in Atlanta with more time. He's got a really good offensive mind, but holy shit is he twitchy and weird.