From my experience in remodeling, and using different cordless brands every day, here is my opinion:
1. Do not buy Bosch and Metabo cordless. Big waist of money and batteries are crappy. The Metabo was the biggest waist of money for me. Their top of the line 15. 6 hammer drill lasted less then 1 year. The first dead battery was there in less then 2 months.
2. Buy DeWalt, Millwaukee, and Makita, and probably in that order. The first two have taken abuse that no other brand has survived in our hands. I'm talking about 18v DeWalt and Millwaukee with NiCad batteries. Most of my friends- plumbers, electricians, carpenters use these two brands and nothing but those. Can not go wrong.
I bought the new Makita 18v LiIon hammer drill and impact driver combo. I like it. Seems well made, tough. Strong performers. Batteries last longer then older NiCad, which is expected. I hope it lasts as the other two. Time will show.
2. The best drill/driver for all day work for me- Panasonic 15. 6 3ahMH batterries. I've had it for 7~8 years, and it's still a dream to use. Incredible balance, amazing batteries, good weight, the best drill for a carpenter. Not a heavy duty, workhorse as the above two, but if you do not need the extra girth, the Panasonic is in a league of its own. Now they have 3. 5 Ah batteries if not better. Panasonic makes the best batteries hands down. I have never replaced a single battery on it, yet. And I use it pretty much daily. You can drive screws for hours, and your arm will appreciate the low weight.
I hope you get what works for you.
Ilian