My Vote..
OK, lets make a couple of assumptions here. First lets assume the plane is set up so that it will at least travel in a straight line on the ground as you power up (definately NOT a given with some beginners trainers I've seen!). Second, lets assume that when we say landing, we are talking about something that is at least semi controlled and that the plane can flown again after it occurs!
If the above assumptions are stuck to, then I would have to agree that a CONTROLLED, SUCESSFULL landing is much more difficult for the average beginner. With that said, I can say that in many years of instructing, and more students than I can remember, there was only one that I can remember who started aceing his landings before his takeoffs....
Lee