Before I get to temp - let me explain my process. I cook open until 165, then wrap in "Foodservice Film" aka saran wrap on steroids. That plastic wrap will hold up to 265 degrees ( I cook at 225). I put the brisket back on.... let it cook to 190, then throw in a cooler to rest for a couple hours. typically after 45 min or so, the internal temp of the meat is 195. It continues to cook then will hold that temp for quite a while. After about 3 hours in the cooler ( you'll still need heat gloves to grab it) I set the large package in a pan, cut through the saran wrap to capture all the juices and then let the brisket rest for slicing. From my experience, that makes even boot leather tender, juicy and flavorful. We have salvaged some tough briskets by doing that to them after they are cooked.
Ok - so having said all that - 195 is the temp I shoot for. I usually get to that temp an 30-45 min after I have pulled it off the smoker.... Take that advice and 50 cents, and you can get a good cup of coffee