The most like surfing, or the most good for surfing.
Surfiest is a word that talks about how good something is for surfing. It's a fun and positive word.
Examples:
The beach with the big waves is the surfiest.
This surfboard is the surfiest one I've ever seen.
She found the surfiest spot on the beach to catch the waves.
The surfiest beach is the one with the most waves.
He's the surfiest person I know, he can ride any wave!
The surfiest waves are the biggest and most exciting ones.