So....

What is a big wave?
Whats your ideal wave size?
How do you measure waves? I measure in head heights.

here's my view.

Up to shoulder high Small.
Head to double head Medium.
double to tripple head BIG
tripple + monster

My ideal wave is probably 1 to 1.5 head. Double head gets pretty ring puckering.
Anything above double head is pretty terrifying.....