Hi there.
Personally I would choose Gigabyte or Asus. Which exact model you find in your local area might dictate which. As for chipset, I think the B760 is a sweet spot and a lot cheaper than the Z790. So I would look at Gigabyte B760I AORUS PRO DDR4 for example.
I am aware of the ASRock ITX models and have used them in the past but they often have unique little issues which make Hackintoshing them trickier.
As for 14th Gen compatibility for a Gigabyte model you would need BIOS version F8 or newer for that. So any need for flashing will depend on what is shipped to you. I have built 2x Gigabyte B760 based Hackintoshes and both motherboards needed flashing before I could use the 14th gen CPU.
Hope that helps.