Both voice and animator are important pieces, it's just that sometimes one seems more important than the other. For instance, can anyone remember (who is not a total fanatic or super movie buff) who voiced Ariel? Aladdin? Belle? The Beast? I just can't. Their voices certainly fit the art and animation, no doubt - but that's what they are supposed to do: compliment each other.
The trend today is to cast big name star power in as many roles as the budget will allow. There's something to be said for this, but it also causes the importance of voice to tower above the art and animation, and I don't think that's fair.
This is an especially pronounced problem in computer animation. Since the common perception of computer animation is that the computer does all of the work, the public expects to hear a "star" voicing the characters because they feel that Such-And-Such is not only lending his/her voice to the character, but also all of the animation reference and interaction, etc...
To sum up, both are equally important. The animation must fit the voice, and the voice must fit the animation. The relative levels of talent and skill involved in either voice acting or feature animation is another discussion entirely.