My choices in order:
1- B&M Hyper - Reasons: The restraints are so comfortable, the ride is so re-rideable and the ride is so frackin' fun. I have been on 3 B&M hypers now, and all three are in my top 5. And Diamondback is my #1 steel. So you can see what I think of them.
2- Intamin prefab woodie- I have yet to ride one, but they just look insane and great rides. I don't think this would ever happen though, considering the park has 3 woodies already.
3 - GCI or Gravity Group woodie - The 2 GCI's and 1 Gravity Group wooden coasters I've been on were all great and I'd love either builder to show up at Carowinds. I'm not as big a wooden coaster fan as Jonathan, but I do love a good, fast, smooth, insane wooden coaster. Did I mention Beast is running good again?
4- Intamin hyper - I've only been on DC's Superman (and Millie if you count it), so its probably not fair to compare but I just didn't like the experience nearly as much as the 3 B&M hypers I've been on. Plus I don't like their t-bar as much as far as comfort goes compared to the B&M restraint.
EDIT: Actually after looking at my top 10, the 3 B&M hypers are my 1,2 and 3. Millie is #4 now.