1/2" Drive will be more useful for automotive work. If it were big trucks, another story maybe. I even have a 3/4 to 1/2 reducer and on things like the yoke Denny referred to, I just use the 3/4" drive socket with the reducer. Works fine.
Mine is an HF special, so one of these days when it stops being useful, I will get a nicer one. Electric is a good idea if you don't have air really handy. I was surprised at my friends electric one. Does more than mine will for sure.
