My vote is Top Thrill 2 and here's my reasonings.
1. Son of Beast at the end of the day ran from 2000-2009. 10 seasons.
2. 2006 when the loop was causing problems, they removed it and the ride was back up and running again
3. Top Thrill 2 is a reimagining of Top Thrill Dragster that was only open for what? 6 days? I got to ride TT2 twice with my wife, but most of us haven't gotten a chance to ride.
4. If TT2 was never to reopen and became a complete fail, then that means they wasted tons of money and others hopes and dreams to ride it and built the hype for this new attraction for nothing...