The gun of course. That's why half of all suicides use one. It takes time to die the other way and people change their minds given time.
So tell me. How exactly does someone who is passed out change their mind?
The method makes zero difference to someone who is intent on killing themselves.
The method makes a great deal of difference. The longer it takes and the harder it is the less often if happens.
So how long does it take to leap from a five story parking garage?
Quite a while actually. First you have to find one, then you have to get to the top, then you have to climb up and stand looking over the edge and decide to jump. Most don't but jumpers are the most serious suicides of all. You need balls to do that, and it takes a lot of planning. I've stood on the edge and jumped, with a bungee of course, just to see what it's like. One, and done.