I bought one a few years back from a SUP shop. Asked him the difference between like a BIC and Connlley or the like and top SUP brands.
He said the BIC was pretty cheap, (yeah he wanted me to buy his stuff) and that the stuff from ski companies was mildly better.
That said I ended up buying a Starboard 12'. Super stable, I can bury the rail and have water covering 4" and not issues. Paddles well, not as fast as a touring or race style but it goes well. Best part is that the wife and I can put a kid or two on it with one of us and just go. While not suggested we can also grab some drinks and a cushion and I paddle while my wife sits. Granted we are light and under the weight limits.
That said I am glad we spent the extra dough after looking at what Costco and places like Dicks or Scheels sell. And I can stop at the local shop with questions, service or if I want to sell mine and upgrade. And when we do it will be for a smaller more challenging board or a touring model.
Naish, Starboard, Idol all seem to make good boards.