I use a combination of Apeman C550 and C370. I originally bought a C550 for the front, but didn't like the rear camera quality, so instead put a C370 at the back. I now have the same setup on both of our cars. I wouldn't make exaggerated claims for them, but so far they've worked OK. I also use their add-on GPS unit on the C550s so as to show my speed.
I like the fact that they're small, discreet and stick on to the screen - I hate suction mounts. The downside is that, like many cameras, they show the reflected image of the dash in the image, as there isn't a CPL available for them. The considerably dearer, but very similar, Viofo A129 has an add-on CPL.
If I were going to replace the lot, then I'd probably go for something like a Thinkware or Blackvue with a CPL.