If you are looking for best bounce I would gp rectangle but it would be pretty small because it would be cheap. I have a zupapa circular and I just set it up in an oval shape to get more pull out of the springs. This will make you go higher so you can do more tricks. You could also look into an octagon as I have only heard good things about them and how high they bounce.
"When you fall you always want to land in the afterbang position for maximum steeze"- Andy Parry
check out craigslist for your area. got my tramp last year practically brand new for like 20 bucks and it bounces amazingly. easily can dub it. and its a 16 foot round.
'i hear that putting coke and mentos in your ass gives you the same high as marijuana.'- *TACO-DOG*
"Dude if you dont want kids rolling over the jump, then dig holes behind it, make it a tarp" Josh Kennedy