To start, if you get the i5, you need dual channel RAM (2x2 GB) not triple channel (3x2 GB). Also, the board in #3 is better than #2.
Regardless, the i5/5970 is the best gaming build there. You may want to consider getting the Asus P7P55D-E Pro as the i5 board for the Crossfire options. Also, if you want to add a second 5970 later, you'll need an 850W PSU.