Some of my trips are exclusively by land, others by cruises and some part land and part cruise. I have also been on riverboat cruises. I have been asked which do I prefer. Sometimes I have done cruises just to accompany friends or my mom, who prefers cruises. On other occasions because of the itinerary. The drawback with cruises is that you are only able to stay in the port/country for four to eight hours so what you really get is a glimpse of the country. In few instances a ship might dock in a port for overnight which gives you some more time to explore. The upside is that you don’t have to keep moving/packing, that is your home for the duration of the trip 7 days, 10 days or more. The other thing that is good all your meals are included and live entertainment is everyday.
With land tours it surely gives more time in one place and you can see more and do more. Depending on the tour, meals might be included and if not dining could be expensive. It is all about preference. When you go by ship or riverboat there are always tours arranged by the cruise line which might range from easy to strenuous activity but you have choices. If you are travelling in a group you might want to plan your tours independently prior to arriving at the port or upon arrival at the port of call. Be mindful of the time because there is the potential to be left if you are late for departure. If you are on a tour arranged by the cruise line and they are late in returning you will not be left behind.
So to answer the question, I enjoy both and depending on the port of call time allotted is sufficient and if I find the place warranted a longer time I might find a trip that allows me longer time. For the land tours I have taken most could not be done by cruise anyway and allows me enough time to delve deeper in the culture of the country.