Kumhos are directional, so no side-to-side rotation... other than that, I also hear they're loud (if you care) and the wear isn't supposed to be that great. Someone here has them, and they can tell you about them
BFG MT's (old style) are becoming harder to find, IMO, unless of course you go with that one size that is OEM on the Jeep Rubicon.
KM2's are promising-looking, but I'm not sure how they'd hold up to the rain... no siping really, and the tread block looks like it'd be pretty poor against hydroplaning.
Bill ran the Procomp Xtreme M/t's, so he can let you know how they were on the road and off, I believe they are made by Cooper Tires. I plan on going with these or Cooper Discoverer STT's next time I get tires, as the rain handling is important to me as well. I also like the side lugs and the tread.
Procomp:
Cooper:
Another possibility could be Firestone Destination M/T's, which I hear divided reviews on in regards to wet performance. Supposedly the different compound makes them better in the rain. No siping whatsoever, though.
Maxxis Bighorn Radials could also work for you... They've been tried and true for many people in the expedition world.
Another tire to look out for is the Nitto Trail Grappler and/or Mud Grappler. These tires are super expensive unless you have a hookup usually, but they are supposed to be pretty good, the Mud Grappler has siping, and the Trail Grappler is a nice hybrid AT/MT, leaning very heavily towards MUD. Size availability isn't that great, though I heard from a Nitto rep that they're releasing the Trail Grappler in 285/75/16 later this year. Then again, you're also in Toyo Open Country M/T territory at this price range. Just some more food for thought.
Trail Grappler:
Mud Grappler:
Open Country MT: