There are many awesone crews in One Piece.
The strongest crew according to me
is Big Mom's.
I mean look at her crew. She has so many sons and daughters which have there bounty above 500 millions. She her self is a Yonkou. She would have a bounty of 1 billion.
People might think it is BB's crew.
Well it is damn weak. His first commander burgess was defeated by Sabo. So weak. They have no Haki to beat logia
But if we add BB then we might get 1 billion but it would not have more total bounty than Big Mom's crew. It is out of question
Kaido might have a better total bounty than Big Mom's crew but it is hard to say. Kaido mostly have all his crew members using DF.
But Big Mom have more crew members than him and therefore 'More Crew, More Bounty'.
If you want to pont Shanks then I would say that
Shanks doesn't have more than 400 members while Big Mom has more than 500 members in her crew.
Though they are strong but Big Mom's crew members are also strong.
Therefore I came to conclusion that Big Mom has the strongest crew.
But that doesn't mean that She can beat Shanks or other Yonkou , one vs one.