I say the BTTF 2 Del. The first one used to be my favorite, but its too much of a hassle always having to go back for Plutonium and the fact that it randomly dies. I love that the second one is unlimited with trash refuels, and the fact that it can switch between flying and driving. Almost like a plane that can drive I love the wheel and Mr. Fusions animations The only bad thing is when it can get struck randomly by lightning and the time and flying circuits get fried