64 GB Viofo card that came with the unit. The card can hold approx 2 hours of video, which is enough for me. Personally, I think it's better not to have too much evidence of my own mistakes on the card
I've been using a Samsung Evo Plus 128gb UHS-I U3 for about 2 years now without any problems. 1.5 years in a DOD RC500S (until the dash cam died) and now in a A129 since I bought it in June this year. I've also been using the high bitrate mods from BCHobbyist with the card giving no errors at all. From my experience I highly recommend them even though they are not recommended for dash cams. But don't use them in a Thinkware...they will give memory card errors. I've been using the Sandisk Ultra A1 UHS-I U1 cards without any issues in those.
Viofo Australia are recommending and selling the Samsung Pro Endurance and Sandisk High Endurance cards up to 128gb on their website. If Viofo themselves are recommending these cards then they must work in all Viofo dash cams. What I found interesting is that they aren't selling any Viofo branded sd cards though