Great topic. I never rode roller coasters until my senior year of high school when we took our senior trip to Orlando, and I just thought "

it. When am I going to get this chance again?" I rode Space Mountain, and some of the other Disney coasters. Then, at Islands of Adventure, I rode The Hulk coaster. I took another trip to Orlando a couple years ago, and I have to say, Islands of Adventure/Universal has the best rides. I don't care how many twists/loops/drops the ride has as long as I feel secure. It's that "single lap bar, sliding around, feeling your ass lift off the seat" shit that freaks me out.
On that subject, a few years after my senior trip, I was still feeling brave and decided to ride the Cyclone at Coney Island. For anyone who doesn't know, it's one of the oldest wooden coasters in the country (built in 1927) and was deemed a New York City landmark in 1988. Just looking at it, you wouldn't be very impressed, but because of what a huge piece of shit it is, it was without question the most terrifying ride in my life. It only has the single lap bar to hold you in, and the drops are actually big enough so you can see the front car as you plummet (I was seated in the latter half).
Add to that the rickety shaking that rattles your bones the entire ride, and you've got one miserable experience. As I felt my ass lift off the seat, my distrust for the ride compelled me to physically pull myself back down. When the torment finally ended, my back was actually in pain from the constant shaking. I can appreciate that this is one of the oldest roller coasters left in existence, but what a piece of shit. There's a reason people don't play football in leather helmets anymore.
Here's a POV of the Cyclone. Like I said, it doesn't really look like much, but you can almost get a feel for how bad the rickety shaking is.
http://www.youtube.com/watch?v=ajz-tzyp3FQ&feature=fvst
For comparison, here's The Hulk coaster which didn't bother me at all.
http://www.youtube.com/watch?v=jVdZROJf9Ag