We get asked a lot what brand and model of SD cards we use in our own dashcams and what other brands we recommend. Personally I am running a Thinkware F770 which supports cards up to 128GB. It comes with a high quality 32GB Micro SD card which work very reliably and offers good durability but the 32GB size is not ideal for those with a 2-channel setup and want to run parking mode. In Parking Mode situations, the incident may not have been caught until a few days afterwards so it is at a high risk of getting overwritten. Once the video is overwritten, there is no way to get it back. With a larger memory card, you have a larger safety net before that video gets overwritten.
32GB memory cards are a great option as they don't have compatibility issues with Mac computers and they're cheap enough to replace if they go bad. Micro SD cards in dash cams typically last between 6 months to 1 year before they need to be replaced. Certain dashcams like our BlackSys and Blackvue models require a FAT32 formatting on 64GB or higher cards which is natively incompatible with Mac. There are special ways to format these cards to work on both Mac and the dash cam however. For Mac users we generally recommend the Thinkware lineup as they use an EXFAT formatting which can be read natively by Mac computers
Personally we are running the Lexar 633X which is also what we are including with our 64GB/128GB bundle options. This card has performed very reliably in our experience and we've never come across any issues with it. Lexar offers a limited lifetime warranty for their cards and customers can go through the manufacturer for any warranty inquiry.
SanDisk is one of the least reliable Micro SD cards for use in dash cams in our experience. Even with their specially designed Sandisk High Endurance cards, we've had customers report issues with their dash cams that didn't occur while running other SD cards. SanDisk cards do work well in other applications but apparently the memory controller they use can cause instability with dash cams which manifests as random restarting or simply a failure to record.
We get a lot of feedback from customers who experiment with different brands and are always happy to forward that information on to other customers wondering about the same issues. As always, it's a good idea to be formatting memory cards at least once a month and it's usually quite easy to do on the device itself (ask us if you don't know how!) and check regularly to see if you are missing files or if the performance is not up to par.