I was an electrician for a brief period and what I bought and what everyone else had on their belt was a 12v compact Dewalt Impact. Next up was probably Milwaukee and third most common was Hitachi. Do NOT fall for Rigid's battery warranty at Home Depot. I almost did and was SO glad I didn't. The M18 fuel stuff is solid if you don't mind weight and the new 20v brushless impact from Dewalt is the cat's ass! So, in closing, Dewalt 12v compact impact for carrying around and the 20v brushless for large jobs that require more grunt and weight isn't an issue. There are kits with both of those in them and the tools included are probably the best in the business aside from maybe the comparable Milwaukee kits. You would be hard pressed to find a trade that relied on their drills more and anything other than those three brands in the hands of electricians to burnt up within weeks/months. There are a couple others (mostly German made) that are better but they're in a different price bracket than the stuff I listed so unless you're using them all day every day to earn a living it wouldn't be worth the investment.
BTW, having left my 20v at work I used my 12v impact to built this entire bench using 3" screws:
Chewed up a boat load of batteries (this is where the 20v brushless shines!) but handled it like a champ and went back to work with me Monday morning.