They're both classics. I'd have to go with The Lion King though. The concept of Aladdin, a man in the slumps rising to the ultimate happy ending of becoming a prince and marrying the most beautiful woman he's ever seen has been overdone today and turned quite cliche.
The Lion King, however, I still find very powerful. I particularly like the scene when Scar has Mufasa on the edge of the cliff as the stampede is going by. Those words, "Long live the king!" It's still moves me whenever I see it once in a blue moon. Also, the comic relief (Timon and Pumba) weren't as overdone as I felt Abu and Iago were.