Pro Great budget option
The Gaming Pro Carbon is an excellent budget option. Because it has most of the features as the higher-end motherboards, like USB 3.1 ports, support for 64GB of RAM at speeds of up to 3200MHz, multi-GPU support, 6 expansion slots. All while costing considerably less.
Con No on-board buttons or displays
Doesn't have any buttons that would allow you to power on/off or restart the system without putting it in a case first. Also doesn't have displays of any kind, which can make troubleshooting more difficult. The only thing it does have is the bare minimum, some debug LEDs. Not a big issue, but having those buttons can save a lot of time if you're going to be replacing components often on an open-air system. And having a display would help a lot with troubleshooting.