There is no brand, even you find one with a brand name, it's probably some companies slap a sticker and call it their own design.
I bought mine for US200 (shipped from China to Hong Kong), US300 shipped to the States isn't that bad.
All these android units are made in China and aliexpress might a good place for you to look around.
I would say look for 2gb ram, 32gb storage, Google Play, Oreo, come with Mazda harness. Oh, by the way, the unit allows you to control with your stock steering wheel buttons, but you won't be able to see the radio info on the upper dash display. Other than that, everything is simple plug and play job.