The Nexus 5 offers as close to 360 degree protection as any dash cam system we've tested via front, rear, and dual interior cameras. It's pricey but takes quality captures day and night with embedded GPS.
The small camera doesn't skimp on features (GPS, Voice commands, phone connectivity, or capture quality. We'd prefer that Viofo improved its lens to include polarization so you don't have to constantly add and remove the optional filer.
The Thinkware U3000 dual-channel (front/rear) dash cam combo takes detailed captures and features a unique low-power parking surveillance mode that utilizes the onboard radar. Yes, radar. You pay for it though.
Nexar's uber-classy One dash cam leverages all the latest technologies including phone connectivity and online storage. The latter, however, is required and subscription-based. Also, captures are so-so for 4K and we experienced serious issues getting video off the camera.