"I vote for:
custom titanium 26er with clearance for 26 x 2.8 tires, and good geometry and bottom bracket clearance for 26 x 2.1 tires
11 speed 1 x 11-46
mechanical disc brakes."

I like this choice, however one thing to be aware of is that should the frame crack it cannot be easily repaired by a garage mechanic. It can only be repaired by someone with the skills, equipment and material to work on titanium. Steel or aluminum frames can be repaired by most people with a tig welder.