I've had classes from CCK and from Eskape, and was pleased with both.

Before buying our own boats, we rented from CCK, Sea Trek, Aquan, and Monterey. No complaints.

You missed Outback Adventures in your list. No opinion on their instruction or rentals. When I was there, they had a nicer store in Larkspur and a smaller one in San Jose. Now it looks like they moved the San Jose location to Fremont.