First thing you're probably asking is how frequently you see orcas. Given that all the whale watchers in the area use the same network, you won't find one whale watching adventure more likely to see stuff than others.
So that means the difference is with the crew and the vessels they use. I booked 8 trips, at the time of writing this review ive been on 3, but thats all I need to be able to write a review.
The crew is highly knowledgable about the islands and their history, not just about orcas. That being said, their knowledge about the local orcas is unmatched, able to identify specific individuals almost on sight. They are incredibly welcoming and friendly, they are always ready to answer questions regardless of how silly you may feel about asking them. And they are all passionate and seem to love what they do.
I consider myself very knowledgable about orcas, and in 3 trips ive learnt tones of things I didn't. Ive seen orcas on 2 of these 3 trips, and the one I didn't I was offered a voucher to go again.
Another thing I want to commend is how strictly they follow the rules of whale watching, and how respectful they are to the wildlife we come to see, and not only that, but are also supportive of the restrictions. Theres a right way to watch whales and a wrong way to watch them, these guys do it the right way.
All that being said, if you book to do whale watching, you shouldn't just book a single trip. Whale watching is finnicky, sometimes the whales are just not there on the day, thats out of anyone's control, its just a fact of whale watching, so I would recommend if you really want to see whales, book more than one trip because you can never be sure but you can at least increase your chances by increasing your time on the water.