I have flown all 3 and if I had to choose I would pick in this order.
1. Inspire, its a little more stable than the Showtime and it can flat do some 3D stuff. YNOT flew mine with a 12x6 prop. I now have a 14x4 on it and its got muy pullout power. I think the Saito .82 is probably the ultimate IC engine for it.
2. Showtime, is bigger and every bit as maneuverable as the Inspire, but it can be snappy if you arent careful. Its a VERY close second. With a YS 1.10 it is an awesome plane.
3. Mayhem, basically its a U CAN DO with a better rudder design. Extremely stable and a good 3D starter plane.