You need to use a little patience here. This is the second time that you've done this. Three hours isn't a lot of time for us here in the States as many have jobs and are working while you're posting. A lot of people don't have experience with CEN Racing/Genko Trading boats.
Now to answer your question.
It depends on what you want to do with it. The Aqua Jet is easier to upgrade later on than the Wave Shark. The Wave Shark is better for playing with a rougher water than the Aqua Jet although it will need more floatation foam.