It's funny to me how people have these debates and act like Brady was a static caliber of player for the whole 2 decades. Part of what made him such a special player was the way he tirelessly worked to reach the levels he did. He won 3 super bowls before he ever made an all pro team. Pretending he was the same caliber of player in 2018 as he was in 2001 is an insult to the work he put in to improve.
The Pats won 3 in 4 super bowls from 2001 to 2004. That's been matched in history and there were teams who did it more dominantly. Then they won 3 in 5 years later on, which was also matched in history (and again by KC just recently). What wasn't matched was the 2 decades of sustained dominance and annual Championship game appearances. Brady wasn't good enough at the start of his career to carry teams and he doesn't win those rings to pad his legacy without a GOAT coach/GM in BB. By the end of his career though, his GOATness was carrying some of BB's outdated coaching and scouting methods to a couple extra years of shelf life.
Players are always more important than coaches. If you can only take one you take Brady, easily. Although you do have to acknowledge the role good coaching played in his development too. But still, it's easy Brady if you have to divide up a pie of credit. But without both you don't get the 2 decades straight of success that is their all time differentiating factor in NFL dynasties.