I have owned several sets of BFG AT's. They are very good tires and should last you 50k miles. I found they start lacking in winter traction when they are about half worn. I switched to Goodyear wrangler silent armor AT's and found them to be a better tire than the BFG's. Better winter traction that lasted the life of the tire, plenty of off-road durability. I have also owned the Mich LTX AT, Cooper ATR and several more agressive MT tires. The Coopers are a good choice as well, but not a whole lot cheaper than the big brands anymore. The LTX was the previous design, but still a very good tire. Michelins might be more expensive but they wear like iron. Those are very likely the original tires on your truck.

Personally I wouldnt fit a P metric tire to what is ostensibly a truck. You will find that typically P tires have less tread depth than their LT brethren. So cheaper might not last quite as long. They also typically use less inflation pressure which in many cases can cause a squishy squirelly ride.

Look for a tire that carries the "snowflake on the mountain" symbol on the sidewall. These are winter rated tires, they will give you the traction you need. I fitted D rated LT tires in an MT tread that has the snowflake. Sure they hum a little but they look great and snow traction, as well as off road traction has been very impressive so far. The truck still rides very smooth.

Good Luck.