The first time I rode Nitro, on the last 180 degree turn, I saw a little bit of G - induced gray creep into my peripheral vision. That impressed me.
The most intense part of Nitro is the 540-degree helix just before the mid-course brake run. I almost always grey out here, and on one of my rides yesterday, I even blacked out, and didn't regain my vision till after the mid-course.
Good riddens to it. I rode Rolling Thunder pretty to close its end of life, it was one of the only times that I have been legit scared on a rollercoaster. The thing felt like it was going to shake itself apart and derail. I'd rather ride Predator at Darien Lake than have had to take another ride on Rolling Thunder. There is a difference between devastatingly rough and feeling at the limits of safe operation.
I rode Rolling Thunder on its last day ever. It was definitely at the end of its service life. It shuffled a lot on the turnarounds, and there was lots of jackhammering in the valleys. For many years, Six Flags had a lot of deferred maintenance, and that really did it in. I've never been on Predator, but I've heard it's pretty unrideable. It has been partially retracked with steel Titan Track from Great Coasters International (GCI), so it should be better now.
My only time there was October, Nitro was crawling, I have no idea why people think it is one of the best B&M hypers.
I've been on Nitro many times, and it's always been a fun ride. It was even my first full size coaster, when I rode it for the first time in 2007. I've only been on one other B&M Hyper, which was Goliath at La Ronde, so I don't know how Nitro compares to the others.
Most roller coasters run slower in cold weather, particularly when they are not warmed up yet. My guess is you were there on a cold day. On a hot day when the trains are running at full speed, the first half of Nitro is better than the second half. But on a cold day, they sometimes disable the mid-course brake run. This means the second half has stronger airtime than usual, but this also means it'll be running very slow in the first half.
I never got a chance to ride KK, but Toro is without a doubt the best wood coaster in the country, and best at SFGAdv by a long shot.
El Toro is definitely the best in the park, and one of the best coasters I've ever ridden. I've been on Kingda Ka several times. Unfortunately, it has a lot of downtime. Not only does it have mechanical issues, but it can't run in high winds or any rain at all. That launch is really something. It kind of knocks the wind out of you.
