Snapper by their very biology are covered in scales ....tend to have smaller mouthes than kingies.........so if i had to chose between net and gaff for them......100% a Net.......Snapper also have lots of spikes and razor sharp cutting edges that will rip you to bits if your not careful.....

Kings 100% a gaff and lip gaff them if intended for release......Big mouth......But a solid set of lip grippers would be first choice on the boat.......an extendable gaff or net for the rocks but needs to be very strong......rocks can be slippery....so the extendable gaff or net is very good for safety with the flow of the tide.when lifting fish from the bricks with a net (particularly) or a gaff........both need to be vertical on the lift with big fish or you could have an L shaped pole pretty soon !

P.s some of those lip gripers come with scales in built......so you could weigh at the same time.