This 'fun meter' is a relative meter that shows how much fun you will experience on the trampoline.
In general you can say that the bigger the trampoline, the bigger the amount of fun you will experience. It is also the case that rectangular trampolines jump best, followed by the oval trampolines and finally the round trampolines.
Elite and Champion trampolines have AirFlow and TwinSpring. This combination also provides more fun for the jumper.