I have a BOSCH 19.2 Volt NI MH drill, but jesus is it heavy, seriously would not like to use it all day, but awsome power, especially on slow speed, was £200.
Comes with two batts and a quick charger.
All batteries will lose charge when not in use, more so with certain types ie NI MH, but LI PO(lithium Polymer) is even worse for losing power, but do have awsome capacity.
As said depends what you are doing, my face all time one is the makita I had, did everything nice and light, spare battery, not too dear.
tabetha