What year X do you have?
Do you offroad much, or mostly stay on the pavement?
What kind of lift do you have?
What do you want your new tires to do that your current ones don't.
Here are some additional thoughts:
When I was shopping around for tires, there were more options in 285/75/16, and they are typically cheaper, but thinner than the 305s. The thinner tires fit a little cleaner on the stock 16 x 7 rim...but you don't get as much of the cool balooned fat tire look that everyone loves. The thinner tire allows more clearance when steering, which is nice for a street driven truck. The fatter tire has to run at a lower tire pressure...otherwise the balooned shape will wear the mid section of the tire down faster. You have to lower the tire pressure enough to let the tread lay flat.
I ultimately had a similar size decision: 33 x 12.50 or 33 X 10.5. I went with the 10.5s, and don't regret it. It fits great on the stock sized rim, tucks nicely in the fender when flexed, and steers a decent amount before rubbing on the frame. Of course, many people run the wider tires with no problems...so it is a personal preference.
The BFG AT KO2s have a great reputation of having great street manners, low road noise, and awesome tread wear.
As mentioned, I have never had these before...but I went with the BFG KM2s and was very satisfied with the quality and performance. I would expect a similar experience with the BFG KO2s.