Scared: Since nothing really scares me now, I'll go back to what I was scared of the first time I went to Disney when I was 5 - Snow White's Scary Adventure and Pirates of the Caribbean. I HATED them. I hated Snow White because of when the ugly witch pops out and I hated Pirates because of the gun shot noises. I also recall screaming my head off as my dad carried me all the way from the World Showcase to our car because I hated the fireworks (I think it was before Illuminations). I still have issues with fireworks (and lightning too, it's the loud noise + something fire related for me) but I will sit through Illuminations if I positively have to and I do actually really like Wishes.
Sick: The only one that has really made me feel sick was Mission Space the first time I went on it - that was when it was still in previews. They've since turned it down a lot so last time i rode, i was perfectly fine.
"I'll Never Ride This Again!": Well, I'll ride pretty much anything at Disney again but I never want to go on Stitch's Great Escape. I thought Alien Encounter was lame and I don't really care for Stitch so that will probably be a ride I never go on. As far as absolutely hating a ride and never wanting to go on again, that would go to the Dueling Dragons at IoA. I went on one and man was I nauseous! My dad was like "now let's do the other one!" Mom and I said "No thanks, you do it by yourself, we'll go back to Dudley Do-Right!" lol