Depends on use. Personally, I like Dewalt 12 volt, 14.4 for heavier duty. If I can put holes in red iron (structural steel) for electrical work, 12 volt seems good enough, and it is much lighter than the larger drills.. Heavy work or work at a construction station, corded works best. Also, corded drills are cheaper, so that may be the consideration if you are only using it for occasional work around the house.
For cordless drills, I only look at Makita, Milwakee, and Dewalt, although I do not know much about Rigid. B&D, Sears, and Ryobi tend to be less reliable brands.
Sold drills for Sears for a while, the TX electrician (commercial/industrial).