1. One of those motherboards is for an AMD System...
2. Gigabyte motherboards are something I tend to avoid, and for good reason.
3. That intel motherboard is a micro-atx, I would stay far away from overclocking on a micro-ATX motherboard.
A. You are in the right area, Z77 is what you want.
B. Asus is one of the best brands to buy from.
C. ASRock over Asus, any day, they offer some of the best motherboards at a lower price, the software packaged with ASRock hardware is pretty bad stuff, so if you go ASRock, do not install any of their pre-packaged software.