I read some reviews on many models.
For the bosch owners, one thing that kept coming up was that the bit holder was too big so it made the bits sloppy if you're using standard bits. Is that something you've noticed? I'm guessing they might have fixed that by now. I know I tend to use a universal holder and swap out phillips bits, nutdriver bits, extensions, 1/4" square drive for sockets, etc.
For the M12, have you had battery issues? That was one thing that seemed to come up with that model. Many youtube videos of appliance repairs have guys using the M12. Just something I noticed, not that anyone was touting them, just using them.
I've liked my current dewalt cordless hammerdrill, flashlight, and recip saw (although I had to do a return/replace on the drill soon after I got it as the clutch system grenaded). They are just too heavy/bulky. I use the flashlight a lot. I know my 18v stuff won't work with the other dewalt stuff so I don't need to stick with it. For appliances I don't really need a drill as much as a powered screwdriver.
I know black & decker stuff is typically not the highest quality. My luck with them has been hit and miss. I was wondering if anyone uses those daily? One review online had some appliance guys recommending the predecessor of this http://www.amazon.com/Black-Decker-Li2000-Rechargeable-Screwdriver/dp/B005LTNLDS/ref=pd_sim_hi_5?ie=UTF8&refRID=11BNBN8GX5M7RDYTYEFA
I'm a bit leery but it is cheap. It doesn't seem to have quick changing batteries which is a big negative for me.