We just did our first cruise with
DCL. It was only a 3 night cruise, way too short, and my 7 year old son spent an hour or two in the kids club each day. He loved it! With such a short cruise, we wanted family time, and he wanted to be at the pool, riding the AquaDuck, doing the mid ship detective agency, up on the sports deck etc. He enjoyed his time in the club, and also enjoyed his time doing lots of other things.
Another thing we appreciated with DCL was the thought put into dinner seating arrangements. We have an only child DS, and they paired us with another family with an only child DS one month older than ours. It was perfect! DS had a buddy to talk to at dinner, and they convinced us to hit the sports deck for mini putt together every evening after dinner.
I actually recommend doing WDW after the cruise. We did a few days at WDW before the cruise, and a few more days after the cruise. Getting off that beautiful ship and going straight home would have been way too depressing for us. I could barely make myself disembark to go to WDW!
Edited to add that my son loves going to WDW, but is absolutely begging to go on another
Disney cruise. If he had to choose between them, he would choose the cruise.