We've done both Aruba and Cozumel.
IMO the Cozumel one was much better. Most of the riding was done on sand, but it must have been heavy sand as we expected the jeep in front of us to kick it up at us, but it didn't. The ruins we saw were nice and the ocean was just magnificent. There was a luncheon served on a beach with time to swim. A really nice day.
On the Aruba one we got to see more things, but I chewed gritty dirt for hours. We still had fun, even though when we arrived back at the ship we were filthy black with dirt. However even though we saw more we had lots more fun on the Cozumel one.
For both we went through the cruise lines and both had excellent guides. However on an earlier trip to Aruba we had taken a tour of the island and seen the exact same things that we did on the Jeep Tour (ruins, ocean, stacked rocks, natural bridge, small old church), but have never seen the part of Cozumel that the jeep took us to while on their tour.
Hope you have fun not matter which one you choose!
