The good news is that there's no wrong choice here.
I was in the same boat as you a few years ago--hadn't ever been to Disneyland, hadn't ever done a cruise, had done WDW countless times. I ended up doing Disneyland and then DCL within the same year, and they're two hugely different experiences, and both worth doing.
Disneyland is more similar to WDW in terms of being an on-your-feet vacation, the attractions, and so forth. I really enjoyed seeing what was the same and what was different, and it was weirdly satisfying to see the original versions of things. So if you wanted a WDW-like experience that has a few surprises for you, Disneyland's a great move. It's only half as many parks as WDW, true, but we happily filled the equivalent of four full days there.
The cruise is a whole different animal. While a lot of the theming carries over and there are characters and so forth, it's a much different vacation feel--and a much slower one. You can keep busy throughout the whole day on the ship if you choose to attend lots of activities, but even then it's mostly sedentary stuff (trivia games, bingo, etc.). The exception is if you do Star Wars or Marvel Day at Sea; my own cruise was an MDAS itinerary and the actual Marvel day was very hectic and almost overwhelming--but tons of fun for me as a Marvel fan. I had a fantastic time on my cruise--while I don't have a burning need to do it again (at least not solo), I'm glad I went. The one anti-cruise thing I'll say is that I personally don't see cruising as a good way to visit other countries--you end up with extremely limited time in port, and the port area I experienced in Cozumel was extremely touristy with a lot of pushy salespeople. I had a better time when I went back to the ship and just spent the port day relaxing by the pool. That's partly down to one's traveling style, though; I like to be able to just wander, and it turns out that's not necessarily an option--you're probably better off making arrangements for an excursion or to go to a resort beach if you're going to get off the ship.