Well, I think 20s are becoming a stock option more more often so we'll be seeing them for a long while.
Personally, I would not want 20s. The 16s have been going the way of the dinosaur and 17s (and up) are very common on these younger model trucks. Makes for some darn expensive tires! Especially if you look for tires labeled 'BFG'
I think since you go offroad a little bit and the truck is a daily driver, stick with ATs(all-terrains). While more expensive than straight street tires, they would wear and perform better on the truck.
Evan made some good suggestions with the Coopers (I've ran STs several times on the old Ramcharger 4x4) and they are more affordable. The tires I have on my 3.1TD Isuzu 4x4 right now are stock Dunlop Grandtrek (snow/all terrain) that do alright. On the '99 2dr Tahoe I ran 285s Toyo Open Country ATs and they did well. I also ran BFG AT/KOs 33s on my '94 K1500.
Honestly, between all these tires the only difference was the price and brand. They all perform pretty similar to each other. So in regards to performance, you're not gaining anything by limiting yourself to BFGs. If you absolutely must get them for the name, well I understand. But you'll end up paying more for it in price per tire.