I have only sailed on Voyager class ship and while it was fun it didn't feel like I was truly at sea.
My opinion was that I would avoid the larger ships after that unless the itinerary was one that really interested me or there was a group cruise and I was cruising more for the people rather than the ship or ports.
I do have to say that if I was doing a family cruise with grandkids a Voyager class ship would be on the short list. There are many activities for kids and I would imagine that this would carry over to Freedom and Oasis class ships.
Take care,
Mike