impact driver with 3" or 6" robertson bit. They don't strip the head but it is possible to overdrive it, especially in wet framing lumber. I use pocket hole screws to build fence gate frames, it works great. My pocket hole stepped drill bit has a 1/4" drive shank so I tried it in the impact driver. That didn't work well because the impacting caused the stop to loosen/move. I found after about a dozen holes the drill bit was going all the way through the endgrain because the stop collar had moved so much. Put the drill bit back in the drill and it works great again.
so Impact driver is good for driving, drill is good for drilling.