Usually, the higher the motherboard cost, the better the on-board sound and other components. Many motherboards toward the $500 range will include PCIe controllers and additional slots for SLI or crossfire with up to 4 discrete cards. The higher-end motherboards are generally more tolerant of overclocking. The more you pay, the more on-board system and cpu fan connectors, USB connectors/ports, and SATA ports you'll see.
That being said, a majority of PC builders need only 1 PCIe slot on a motherboard for a graphics card for gaming. The Micro-ATX form factor / motherboard is ideal for a majority of gamers who use only one graphics card.
If you use more than one graphics card or ever plan to, you'll find a few micro-ATX motherboards supporting two discrete graphics cards, but more competitive pricing in the ATX category for those motherboards supporting multiple graphics cards. Also, the spacing of the graphics cards on the ATX board will make it easier to keep each one cooler.
Depending on the sound system you'll be using, you may need analog surround outputs, HDMI or digital surround outputs off the motherboard. These tend to be found on the higher-priced motherboards.
What kind of sound outputs do you need?
Will you ever run more than one 780 ti in SLI on this system?
Do you plan to overclock your system in any way?
How many SATA ports do you need? USB?
What is your budget?