Case choice
I'm partial to larger cases because I like to tinker with fans and I'm always opening the case for one reason or another. The initial build will be easier with the full ATX case, but once it's done the only concern is temps (will that high-powered video card get enough cool air?) and aesthetics (does it look good and run quiet?), and maybe size (does it fit in my desk's tower compartment?). Beyond that it's a matter of taste. Both the cases you mentioned are decent and well thought out for the price, and both look okay for cooling, so again it's a matter of personal taste. I find that choosing a case is the hardest part of a build, because you're going to have to live with your choice for a long time, possibly through your next few builds (unless you have money to burn and can buy a new case whenever one strikes your fancy). Every time I think I have the perfect case picked out, a new one comes along that I like better! I found that it helps a lot if you can see your case on display in an actual store, pick it up and get the feel of it. You'll find that some of the cheaper cases feel too flimsy and even some of the expensive ones have a cheap feel to them. The good ones are heavy and solid and have lots of fan ports. Corsair, Cooler Master, and Antec all make decent cases. I don't know about Fractal Design, never had hands on one, but I hear good things.