Blackvue 650 based on this forum.
I bought a Lukas LK-7900 nearly two years ago and it is working perfectly, through the Texas heat and the Texas cold. I love it.
Just to add another data point. I owned a LK-7900 Ace for 2 years before I switched (when I got my Tesla) to the Blackvue 650 2CH. I swicthed to get the rear view cam.
Build quality seems better on the Blackvue and the WiFi is nice but in reality, I prefered my Lukas dashcam...
GPS :
Lukas : 0 Problems, even in the Tesla
BlackVue : works 5% of the time. Can go a LONG way without any GPS signal and since the onboard clock is not reliable, your video won't have the correct timestamp!
Temp :
Lukas : runs cools
BlackVue : runs VERY hot. It does prevent fogging in cold temp around the cam, it appear as if the camera as a small defrost feature lol. I also experience the goo on my windshield to the right of the dashcam. Not a big deal but annoying.
WiFi :
Lukas : does not have WiFi but not really a show stopper since important footage is not overwritten (see next point)
BlackVue : has WiFi but transfer speed is VERY low and app is very slow to respond. Only very usefull in aligning the camera.
Storage Management : This is where the blackvue fails miserably in my opinion :
Lukas : Separate folder for "Always-On", Motion (in parking mode) and Event. You assign quota (in %) for each category like 80% always ON, 10% Motion and 10% Event. Events will only be overwritten by newer Events, if the 10% is reached. Ex : you see a crash in front of you : you trigger the Event mode (see next point). The footage will be put in the Event folder. The only way to overwrite it is to accumulate 10% of events footage.
BlackVue : Everything in the same folder. Normal recording, parking mode and events are simply TAGs on the files! If you trigger an event yesterday, i'll get overwritten when the card is full, regardless of what type of recording is happenning.
Functionnality :
Lukas : Has a button to trigger events. Records last 10sec and next 20 when hitting the button. Small LED display you can set to display GPS speed or Time of day or both
BlackVue : No button to trigger events. You need to tap on it... but in any cases, it's not that usefull since the file will be tagged and overwritten by less important data.
Lukas also win IMO for the rear cam connection, they use a USB cable instead of a very fragile coax cable.
Let's just say I'm waiting for a nice, small Lukas 2 channel and I'm dumping the Blackvue. I used to download the event folder every month or so and I had all the important footage.
Quick note for the Blackvue : the latest version supports "Cloud Integration". The camera connects to a WiFi (hotspot or home) and you can use the app to download files / watch the feed live. This is VERY nice but unfortunately only applies to the 650 that were manufactured after April 2015.