To be honest, for the my eyes, the first one looks "better". (Since better is a subjective thing, but you asked for opinions so!)
Former sprite looks more simple, which gives Cirno more distinctive look. Example her skirt frills are noticeable while in the newer they are more ruffled and "detailed". For a sprite of this size, if you add too much detail, it becomes "blurred". So the first sprite gives off more detailed impression, because of the simplicity. Same goes for her face. Former her face is more noticeable and gives an impression of her appearance (bad ass?). The new sprite seems to take away this feeling as she is more looking towards the side).
It depends on though what you want, as sprite animation is relevant.