So many tires, so little money or time to wear them out...
Lots of options, as usual the answer depends.
1) IF you are going to stay with a 255/85 I would vote KM2. Easy.
Though I've had KM2s and didn't keep them, and I like the Cooper S/T, I think the KM2 is generally a more rugged tire with much better sidewall protection/lugs. Also more available.
I understand your 255/85 decision may be forced by clearance concerns and wheels. Surely you can run a 285 on a 7in wheel, but it's not ideal, and maybe control arm clearance is a problem? 255/85 on a 7-inch wheel 'IS' ideal.
255/85 will cost less, and MPG will be better. Depending on where you buy, 255/85 KM2 will cost much less than Toyo MT, and the Toyos are SO stiff you'll have to let more air out to get the same ride & traction.
2) If you open Pandora's Box going with a 285/75, you'll have too many choices...
My favorite remains the F-C II, though I'm always flirting with new girls.
Cooper S/T Maxx was suggested and is also a good option. The Maxx is a bit quieter than the FCII, also firmer, a stout LR E tire with tough sidewalls if that's what you want.
My Tundra drifts right with the S/T Maxx, but that seems to be a problem for me with my lifted Toyotas, can't blame all the tires, just haven't been able to figure it out.