For me it's more about the wave shape and ocean texture than straight size. A classic 3-4ft (hawaiian) wave on our east coast during a cyclone swell is always going to be 'fun'. It's got enough size and juice to have some solid fun without being too much of a paddle out ad typically our east coast in those swells tends to be quite 'hollow' and wally.
Waves like the attached are from our east coast around 3-4ft but wally and steep. The wave on the surfboard is around 2.7m or about 6ft but I only find that size enjoyable if it's not going to close out and actually give a wall to play on. From memory that wave engulfed me and could see it was already closing out 20m down the line so pulled out after the pic.
In contrast, I was out paddle boarding on the same break a few weeks ago in even bigger conditions (likely around 8ft) but the waves were more crumbly and wind-swept. Providing a late drop but then long ride that didn't close out or dump.
I had a blast in that size and condition as it was big enough and breaking out far enough that if you took off right, you'd have a 10-15sec ride with several turns before pulling back in to the channel unscathed with an easy paddle back.
I wish someone had got a pic, I think it was the biggest wave I've ever caught.
Some of you hawiiains might know the brand of the board I've been using. Basically a mini/ gun
