We've been on 43 cruises as well as dozens of land vacations and alot of all-inclusive resorts. Each is different for different reasons, but they're all good.
I'm sure others will have opinions on this, but for us, ocean cruises offer an opportunity to take a wonderful floating motel with good food and see different ports. We don't have to worry about packing and unpacking, where we're going to sleep, how we're going to get there, where we're going to eat, shopping for hotels, restaurants, activities, etc. And if we find a really nice port, we make a note in case we want to go back there and spend some time.
A resort vacation is awesome for relaxing, eating, drinking, and activities. But normally you stay right there and don't leave the property. If you do, you usually have to rent a car or pay alot for an excursion.
And land vacations to see several places have alot of planning involved.
We spent 20 days touring around Europe by train visiting 8 countries and spent another 12 days on a Baltic cruise visiting an additional 5 countries. It was absolutely amazing. But it took ALOT of planning. Needless to say, when we got back, we were exhausted and needed a vacation from our vacation.
Then again, we've spent 2 weeks laying around a 5-star all-inclusive resort doing nothing but eating, drinking, laying around, and taking a daily sail. VERY relaxing!
We've done a river cruise in Europe that was incredible - definitely hooked on river cruises.
Bottom line, it just depends on what you want to do, where you want to go, your lifestyle, and of course your budget. But cruising does tend to offer something for everyone.