Well it really does depend where you current skill level is. I would say the best way to figure that out would be to get on a trampoline and see what you are most comfortable doing.
As far as the least technical goes (IMO) I think that a backflip would be a good place to start. They are physically very easy however mentally can be quite tough. Throwing yourself straight back is definitely an unnatural thing to be doing.
Just remember whatever you try, you will need to commit to it. There is no half ass way to try new stuff. Go for it, and be willing to get back up if you fail.