I got the VW recommended Kenwood DRV 410. It is inconspicuous, but it has a knurled knob to secure it to the pad glued to the windscreen, and it keeps moving. Every time I clean the inside of the screen, I have to re-set it, and aligning it is fiddly. On a 16GB card it records 3 or 4 hours only, then overwrites. I've tried to look back for pictures, even just a couple of days (an idiot driving through a red light), only to find they've long gone. The ONLY way to view the images is to remove the micro SD card and plug it into a PC and use the Kenwood Drive Viewer software.
In my last car I had a hardwired Blackvue 650 with rear camera that plugged into it. Excellent - until I had to relocate the front camera and in the process damaged the plug on the cable to the back camera. That connected to an app on my mobile using its own wifi, allowing me to view or download files. I could also remove the micro SD card if required to copy files to PC to view there as well. I wish I'd bought one of them, and may still do and get rid of the Kenwood.