I agree with Davefr - Panasonic makes the best cordless drill - and has for 20 years. The gap between them and everything else used to be huge - now it's small. I think they still make the best cordless batteries and chargers.
My Panasonic 12v drill/driver was way better than any other tool I've owned up to 18v - they had the best motor control, the best ergonomics and the best keyless chuck I've used, and their batteries lasted longer and charged faster than all the others. Stupidly I gave it away when I bought my Milwaukee V28 tools. I wish I still had it.
It really depends on where and how you'll use it. The Pocket sized 12volt tools from Bosch, Milwaukee and Makita are all good if you have light duty drill/driving to do. They are not as good as a Panasonic 12v (which is true 12v, the pocket tools are 10.8v)
If you have heavy duty drilling, the 18V tools are better and the newest ones are compact. I like the M18 fuel tools from Milwaukee or the 18v from Makita best.
If you are driving screws, an impactor is better than a drill. I have the pocket impactors from Bosch, Milwaukee and Makita, as well as an 18v Milwaukee impactor. Of the smaller ones, the Bosch is the best - although the other two aren't bad. None of them compare to the 18v Milwaukee. I've heard the 18v brushless Makita is really great too, but I haven't used one.
The other consideration for tools is what other tools can share the batteries and chargers. I have not moved to the M18 Milwaukees because the batteries won't charge on my V28 chargers - which will charge everything Milwaukee from my 12v cordless caulk gun to the V28's . Not sure why they made M18 incompatible.