1. Andy Reid/Patrick Mahomes - Kansas City Chiefs
There's really no discussion to have any other HC/QB duo atop this list. The two have been simply excellent since Patrick Mahomes was drafted back in 2017. He got one start at the end of his rookie season, but has been an elite QB since taking over as the full-time starter in 2018.
If he retired tomorrow, he'd be a lock for the Hall of Fame. Mahomes has helped lead the Kansas City Chiefs to two Super Bowl wins in 2019, and Mahomes himself as won two MVP awards and two Super Bowl MVP awards, along with leading the league in many categories across his career including touchdown passes, yards, TD percentage, yards per game, and QBR.
Mahomes and read have gone 71-18 in the regular season together and have also gone 11-3 in the postseason. A combined 82-21 record is just insane. This is this generation's Bill Belichick/Tom Brady without a doubt. Reid is in his mid-60s and probably isn't going to coach much longer, so that's something to watch out for.
Really, the only knock on this duo is Reid's shaky time management and Mahomes sometimes improvising a bit too much and causing turnovers. Outside of that, though, this may end up being the best duo of all-time when it's all said and done.