It could be in Tokyo (bur it isn't) but because we don't know where you are from (please fill in your profile) it is hard to suggest realistically unless you can travel anywhere in the world - and then how would you get your products home?
Dusseldorf, Germany is one of the largest - also NewYork - London, Olympia to name a few BUT biggest isn't always best if you are new to the industry. Biggest can be very confusing and also so many people no one has much time to really talk to you.
thank you very much for all your help. i think i am going to orlando's show. i am having a holiday from 20 to 27 of august. so i will sacrify 24 & 25 in orlando. and the plane ticket is very very expensive. hope things work out and worth the money and the time.