Another vote for the Milwaukee "M18 Fuel". It has more than enough torque for what I'll ever use it for.
The battery lasts too. Just finished replacing the hub bearings on the '06 2500, and the battery did not need to be recharged.

Warning: It broke a couple of Harbor Freight cheap Chinese 'impact' sockets that the air impact wrench couldn't break. It also twisted a 4" extension (it was unmarked...no doubt made in China). Quality sockets are required!