I’ve owned both the rip off lights and the Lezyne versions.
The Lezyne lights are slightly better finished, and have the perfect default flashing modes, in that when you turn the front light on, it stays on steady, not quite the brightest mode. When you turn the rear on, one of the LED’s stays on constant, while the other 2 alternate, which I think makes for a perfect rear light, as did a lot of people I went out with.
However, I lost the front light (my fault entirely), and the battery on the rear light never lasted as long as it should, and got worse over time.
I picked up a few of the knockoff lights, as I figured at least I wouldn’t care so much if i lost them. They’re not so well finished, but they’ve survived some rain and the battery life seems reasonable, and consistent. They don’t have the charging indicator of the Lezynes, although I didn’t trust that anyway. The rubber band isn’t as well designed, and might not be as durable, but has been just fine so far. The flashing modes aren’t as good, but you’ll still be seen, which is all that really matters.
For a couple of backup lights that you don’t mind leaving on your bike outside the pub, the knockoffs are great.