The Lithium Ion Ozitos are really good.
Don't even consider the older type of rechargeables in any brand; the worst Li driver is generally better than the best Nickel-Cadmium of any brand. Fast recharge, no memory, doesn't die on the shelf and most important, it's small and light.
I have a couple of 10.8V Ozitos and am very pleased with them. Power is more then sufficient and the charge is way more than required for any job I'm likely to do. How often do you want to put in more than 100 screws or drill 30 holes? Even if such a job comes up (!) the battery can get a 10 minute charge up to around 80%. Or maybe it's a better idea all round to get a corded item on the job.
My S-I-L has a Hitachi 18V Li-Ion that I have used on occasion. Works great and beautifully made, but far too heavy and cumbersome for the sort of jobs I usually use a cordless for, and I think it cost around $600. It's probably a great tool for a tradesman, but for general use it's like using a Mack truck to get the shopping.
Horses for courses, but I've purchased a number of brand name tools that I've been rather disappointed with (mainly Bosch). A number of the corded Ozito products are cheap rubbish but the cordless drivers are excellent (for "everyday" use).