I have paddled most of the well known beginner-intermendiate ocean-ski boats, but recently I have really enjoyed paddling the Think Evo II's.
I find these boats stable, responsive, and also pretty quick - which is important for many beginners as it delays the need for them to upgrade to a faster boat.
I am 6' 2" tall and weigh about 100 kgs (sorry to mix Imperial and Metric - but I have been the same height from before the conversion but not the same weight
).
I find the Evo II's still have at least 3" foot adjustment left, so even a 6' 4" paddler should still fit easily. In contrast, the old model Evo's (also an excellent boat) have less leg adjustment.
Yes, do I own an Evo II. But as I am now on to my third Evo, I am not getting carried away with new boat enthusiasm! If I was to recommend an alternative for a beginner wanting excellent stability it would be the Fenn XT.
But if you want a boat to use mainly in the surf, then don't get an ocean ski, get a surf ski instead.
That said, I recommend that you do try plenty of boats before you buy.
The key to enjoying this sport is to buy a boat you enjoy paddling. Worry about speed later - if ever - as for most of us paddle for enjoyment not for a living.