I can't speak for the bfg's personally, but have seen them on the trail. for wheelin' take the mtrs. they are more exspensive. not too loud, but pretty tough tires. I have 33" at's on one xj and I love them for dd'ing. My mtr's wore pretty quickly (compared to the bfg at's). mtr's don't hold up to smokey burnouts like at's either (in case you were wondering).
I have over 60,000 on my A/T's and they still have another 10K in them.
MT if you are going in mud/clay trails. The AT will do fine in 90% of the conditions you visit but not MUD, they cake up easy and require A LOT of wheelspin to clean.
With that said, if I had it to do again, I would go with the M/T just for sheer self cleaning capacity.
hell i got almost 12,000 miles out of my 35x16.5x16 boggers on a 1 ton pickup with a bigblock. You have alignment issues if thats all you can get out of BFG A/T's. My 31x10.5x15 A/T's on my ZR2 have got nearly 35,000 miles and are just now under half tread.