round trampolines
The round trampoline is the least safe shape. The reason is because of physics. In a round trampoline every spring points right into the center and makes the center soft. When you move out from the center, the bounce gets harder behind you. If you lose your balance or concentration you may be thrown forward off balance. Fifty percent of trampoline injuries occur when there is more than one person jumping, and on a round trampoline the risk of collision increases. Bouncing on a round trampoline is like jumping into a 14-foot funnel–everyone will go down the spout.

However, because the stress on the frame is equally distributed, a lighter, more cost-effective frame can be used and so round designs are often attractively priced. But don't let anyone tell you that they are safer because they keep kids in the center.