M18 stick light is very first MW light I bought. Not very bright by today's standards but I still love it & use the heck out of it. Got very long runtime even with a 2.0 battery.
Next I got the USB Rover stick light when it came out. I like it too & use it a lot but as everyone knows the magnets **** & are useless to me. Had to work in a warehouse once with no power & that day I was wearing a Dickies shirt, hung the USB stick light with the clip on my shirt pocket & it worked out great.
I've also got the USB Rover pivoting light, the one with carabiner style clip. This one is really useful for me, the magnets are decent & the pivoting makes it handy. But it doesn't have great runtime. Between this & the M18 stick light, I've been using them to work on my truck at night when needed. I don't do much automotive work at night so these do the job for me & I can't justify the cost of an underhood light for my needs.
I bought the M12 stick light simply cause I found a good deal for one on ebay & wanted to make use of my extra M12 2.5 batteries. Never used it it much cause I like the M18 stick better since it pivots & is more stable standing up but now that I have this new M12 pivoting "service" light the M12 stick light may see even less use now. Kind of the same reasoning with this new one (it's what I tell myself to justify it

), I have a M12 6.0 battery that I believe to be a fake, ebay refunded my money for it. It works perfectly fine though, that's what I'll primarily use with this new light & use my other real 6.0s for my tools.
So far I'm really liking this new one. Should be much better using to stick under my hood instead of my USB pivoting light. When it first came out it didn't interest me at all until yesterday when I was looking at it in hand at HD.