At my local theme park the Intiman drop tower FREAKS ME OUT. I have not been on it in years. Im going to try to make myself go on it on my next visit. 
I have heard that other drop towers are just slightly slowed down during the drop to make it less intense but that makes it not a true free fall. 
The drop tower at my local theme park is really intense because it Is a true un-braked free fall. 
The drop tower is called the 'FearFall' Guess what theme park im talking about! 
  
Hint: My country is next to Australia...