IMO, Andy Reid is the offensive version of Bill Belichick. That comparison may not sound right because BB has titles on top of titles while Reid is a notorious choker, and for some reason, Reid never earned the "savant" label like BB did.
But if you watch KC games, this guy's play designs are a step ahead of the rest of the NFL. And he's an absolute quarterback master. Look at the record, he's gone 20 years straight with at least average QB play - developing Donovan McNabb, making Kevin freaking Kolb look good for a season or two, taking a washed-up Mike Vick after three years in prison and bringing his game to new MVP-level heights, leading the surprise Alex Smith breakout, and transforming Patrick Mahomes from a raw, toolsy prospect into a god of football.
As far as offensive coaches go, Reid is an all-timer. Comparing him to a coach like McCarthy, who recycled the same figured-out gameplans for years on end Garrett style, is just insulting.