Start with the 450, and see how much you like it. Yes, the bigger they are, the better they fly (more stable), but the more expensive they are to repair. I started with a few HobbyKing kits, and learned a lot from them (build, repair, repair and repair). I did crash my Trex 450 a few times, and for some reason, more parts had to be replaced. They servos gears for example, stripped on one crash. Never happened with the clone with Corona servos (cheaper and more durable it seems). But after I was comfortable with flying and building, I stayed with Align (bought a 500ESP Pro and then the 600E Pro).