I've been on King Cobra, Riddler's Revenge, Mantis, Iron Wolf, Georgia Scorcher, Chang, Batman TE, Shockwave, and Vortex. Judging by my extensive experience with stand-ups, it would be a three way tie. I'd give it to Iron Wolf, Riddler's Revenge, and Chang.
*Iron Wolf because it was my first stand up, and it's at my home park, so it has a lot of nostalgic value.
*Riddler's Revenge because it's big, fast, smooth, and its not painful at all. I'm 6'3" and stand-ups often make me feel like i'm being crammed into a harness made for someone smaller. I found RR to be very comfortable, and fun.
*Chang because it is also very smooth, and fun. I think Chang was the first stand-up that B&M started using the newer trains, and it shows. I also love the float at the top of the vertical loop, it's much more pronounced than on any other B&M stand-up.
~TodD~
---"Help! Help! I'm being repressed!"---