always get the biggest one possible, even if it means waiting an extra month for your next payday. if you get a smaller one you will regret it i promise!!!
dont worry about the brand and remember, with trampolines you dont get what you pay for. as long as its the right size and it has a net all is good. dont pay over the odds thinking its going to be more bouncy or more safe i know some good trampoline games for kids. will post them tomorrow as im too tired now lol