Rectangular Trampolines
Rectangular trampolines are built to provide a better bounce - A Rectangular trampoline because of the shape and spring configuration causes the springs to work at a different rate, this allows for a more powerful bounce, these trampolines are better for experienced children who are members of a trampoline club, these clubs are where you will find rectangular trampolines.
All trampolines have their benefits and downsides, but generally a trampoline is brought for the amount of available space there is in the garden.
Remember you can always sink your trampoline down to ground level, which will increase the safety. If your children are thinking of becoming gymnasts, then a rectangular trampoline is better suited to gaining more height in order to do a summersault etc