you can't be serious about buying NiCad are you ?
Yes. Dewalt 18 volt nicad tools are cheap enough now and if you get it down to that one battery style you are pretty much all set with a couple three batteries. Eventually you end up with a few chargers so your kits/cases have them and you can put a spare in the garage at a permanent charging station.
It's where I ended up in an effort to have a certain standard of quality, simplicity of a single battery/charger system and of course low cost.
Kurt, I can't buy Ryobi like some can't buy Bose. I know they have feather light batteries, led lights, fast multi port chargers, free batteries in perpetuity, suck start alarm clock coffee grinder esspresso mp3 wave guide digital plungers ...
I think it's important to choose a battery style and stick to it. Batteries come and go so homing in on one that has been around for more than 5 minutes makes sense too. If you love one of your tools, then commit to that ... or just switch over to the 18 volt xr battery style.
Due to work, I'm seeing that the 20 volt lithium ion stuff is considerably better than my bang for the buck choice. If I were starting out fresh and if I had your money, that would be where my money would go. Having a state of the art tool last over a decade works for me. Again, RPM's are where it's at.