Depends. I think drawing them is more of the challenge than actually making them. I mean, sure, the choices are wide and hard to blend right, but that's why there's so many choices :3

The one thing I would find tedious is to come up with something unique of your own xD You have so many combinations of animations in which case you'll be scratching your head and thinking "What should I go for?" :3

Both of those are very valid. I can imagine actually making the frames of animation is harder than just assembling them, but on the "customer" (person using premade animations) side, Minerva has a good point too. There are thousands of animation sets to find, and which to use is the first hurdle to overcome in piecing them together