I think this is the first build I think I've seen on TOMs where someone is actually buying an E-ATX motherboard to use with a FULL TOWER case
My vote is for the Storm Trooper between the two options.
You should MAYBE *depending how much effort is involved* consider selling the 6970 and 560Ti and grabbing a new 7970?
New 6970: $380
New 560Ti: $270
New 7970: $550