29er is just marketing speak for fatter tires on 700c (ISO 622) rims. Fine if you have the frame clearance.

I thought 27.5/650B/ISO584, a comeback of a very old size, was the stupidest idea ever, until I found out more; By being smaller diameter than 622, it allows mounting deeper section tires on road bikes which don't have the frame clearance for bigger tires on 700C/ISO 622. The result is roughly the same outside tire diameter as the skinny 700C wheels it replaces. BIG question on rim-brake compatibility, but with disc brakes, it should be cake.

32s? If a whole new rim size, that's both expensive, and a great way for the bike industry to sell people on a new standard that requires buying a new, expensive bike.

I've been going in the opposite direction, I'm 100% on 20"/406 wheel bikes, with all the advantages of smaller wheels. But I don't ride off road. BMX have been riding 20"/406 forever, and they do it, though on dry dirt. Smaller rims are STRONG. But for max traction in really bad muck, bigger wheels may help, it depends on the "cone index" of the surface, i.e., how soft and how deep tires sink in, but it also depends how much heavier the bike is to accommodate the bigger wheels, as a heavier bike will sink in more, all other factors being equal. Bigger diameter also applies more brake torque for a given ground brake thrust, thus requiring stronger brakes and structural attachments. "There Ain't No Such Thing As A Free Lunch." - Robert Heinlein

"Simplify, then add lightness." - Attributed to several, including Colin Chapman, owner and designer of Lotus Cars.