Board Software
The driver disk included with the ASRock X399 Phantom Gaming 6 is pretty standard-fare, split into four categories and an ads page. ASRock has included some bloatware, but the "install all" list can be trimmed. If you don't want the extra software, click on "install all" and you will get a new window that lets you weed out unwanted items. I would like to see this simplified in the future, with the initial list including the check boxes to trim the install list.
For utilities, ASRock has kept it very minimal. There is App Shop, which offers a wide range of software, as well as a Live Update feature for drivers.
I would actually recommend downloading A-tuning as it has in-OS fan controls for the board. ASRock has a Phantom Gaming skinned version of A-tuning available on their website.
Also included are the "Restart to UEFI" applet, which is very handy for booting straight into the BIOS, and ASRock Polychrome RGB, which is a pretty thorough RGB control app.