I always liked Dora better, the songs and such annoyed me less. Honestly, I was just glad my son watched them instead of a lot of the kids shows out there. Teletubbies, for example, just creeps me out. The baby sun thing gives em the wiggins.
My son used to watch both when he was very young, my niece and nephew do as well. I generally let him pick his tv shows (he was allowed to watch only so much) from the ones I approved. Most kids shows are pretty child friendly these days.