I've used a few types in my time:
Bosch multi-construction hole saws (generally very fast provided no nails or screws)
Standard bi-metal hole saws
Auger bits
Bosch speed bits (generally very fast provided no nails or screws) but self-driving screw soon gets blunt.
Armeg/Irwin stubby augers (generally very fast provided no nails or screws) but self-driving screw soon gets blunt.
Is there a product that will 'hack' through nails and screws without snagging?