I would have too say Intamin rockets that are for strictly height and speed (Ex. Kingda Ka and TTD). They may attract the general public now, but when something taller and faster comes out, they'll all flock over to that. That's when they'll become useless. I give them about 10 years untill they fade away.
My top 3 would have to be:
1. Splash Mountain at MK
2. Kali River Rapids
3. Escape From Pompeii
My least favorite would have to be Thunder Canyon at Dorney Park. Talk about rough! If it weren't for those seatbelts, I would have fallen out of the boat every time we bounced off of the sides. Just way too violent for my liking.
4 and 1/2 hours for Kingda Ka. It would have been much shorter if it weren't for two breakdowns.
Longest wait without breakdowns would be 4 hours for El Toro.