I use a Bosch 9.6. I haven't picked up a 14 or 18 volt drill that I would want to drive lots of screws with. I used my first Bosch 9.6 for 5 or 6 years as my primary when I was doing this woodbashing stuff for a living. It was fine, never had a battery problem, but it didn't survive the shop owner taking it off my bench one weekend and breaking the trigger - grrrrrr. He paid for the repair, but it always had too much runout after re-assembly. I gave it to some guy to fix for himself when I moved.
I lucked onto another Bosch 9.6, basically the same but with keyless chuck about 3 years back. It doesn't get the same kind of use the old one did, but I am equally pleased with it.
I have a Makita 1/2" corded hammer drill for the odd time I need that. I also an 80's vintage corded B&D 3/8" that refuses to die, as much as I wish it would, that gets used when a lot of holes need drilling.