The brands in the poll all have their place, and are all good brands.
I use milwaukee - tough tools with mucho torque - Right behind Bosch in power. I have 3 18v drills, beat the shit out of them and they still run like factory new.
One I use for cement mixing, paint mixing, drywall compound mixing, etc. Smoked the motor once, but still runs like a champ.
My 18v hammer/drill I use for drilling through concrete, masonry, studs, whatever. It's a beast in it's own sense. I dropped it from a 2nd story rafter and broke the casing when it hit the concrete bellow. I replaced the case, resoldered the wires, and it runs to this day in a great fashion.
My other 18v Milwaukee I use for my wood work, light drilling, etc. All excellent drills.
My bro uses the makitas. I really like the newer ones with the fiberglass compound body. Really tough tools, but I haven't got to abuse them (since they're not mine).
At work we run the 18v dewalts. I personally don't like all the different flavors that dewalts come in XR, XRP, XRP+, all that other bullshit. I want an 18v drill period. They're good drills though. Not quite as powerful as the makita, milwaukee or the bosch. I personally don't like the ergonomics vs. the other drills, but my coworkers do. Go figure. I can't tell you the logevity of them, some mfer keeps steeling equipment at work - and his favorite thing is the old dewalt drills (VS our new ones!).
The hitachi's are nice tools, I've used many of their corded tools, and some of their bigger free standing tools. I like those (minus their CR10a2 tables saw - pos - but I digress) and I hear many people rave about their 14.4v drills. Other than that - a blank.
Bosch makes good tools. Never used any of their cordless tools either though. Most powerful 18v if I remember right.
As for places to buy tools:
www.lowes.comwww.amazon.comLowes is by far the best price wise (crepot depot is a tool of the devil).