Aeris was my favorite character in FFVII, but I wouldn't want her to come back. As sad as I was by her loss and as annoyed as I was with Sephiroth (he had some of my sympathy up to that point), I think it served the story better for her to be martyred.

I hope after the events of AC she can return fully to the Lifestream and be reincarnated. She deserves happiness in the next life, even if she didn't find it in this one.