the 18V Ryobi OnePlus system seems pretty robust, i bought in to it a couple of years ago, i give the stuff fairly heavy regular use and nothings failed yet....
i got 2 hammer drill/drivers, a circular saw, a jigsaw, a detail sander, a right-angle drill, 1 all type charger and 2 nicd chargers, and 1 large Lithium battery , 1 small Lithium battery, and 3 NiCd batteries.
the big Li battery is clearly the best, with the most grunt , followed by the NiCd , the little Li is frankly a bit crap, in terms of heavy duty stuff, but handy to keep on hand for when i need a lightweight solution , say when up a ladder, stretching to reach the target ....
the balance is okay, the weight, is acceptable, but not the lightest i've tried.... the torque on the two hammer drills is pretty good, and the lime green is easy to spot in a tool box, or across a busy room /site
certainly better than the B&D or consumer level bosch and wickes own brand stuff i've tried....
not sure on prices, it's worth hunting out deals.... but the big Li battery and charger will eat a hole in your budget.... see if you can get a deal on a twin pack or something.... and make sure it has the "super charger" that does both NiCd and Li, and then get the bigger battery on it's own....