A lot depends on the kind of riding you have in mind!

For example on the Tour Divide, the 29ers are still the preferred bike (hardtail, and often no suspension at all). But last year 4th place went to a rider on a Jones 27+

(Mike Hall had just set a new record of just under 14 days on a 29er).

The Tour Divide is pretty demanding, and only about 2-3% is actually single track. Most of it is either 2-track or gravel and other - things - . About 15 % or so is pavement.

So it seems that the larger wheel with a slightly narrower profile has a slight advantage.

So the kind of riding you do makes a difference!