XT M-771 and here's why!
The Shimano M771 is 6.5 mm wider than the SLX or the Xt m770. Problem is that the plastic spacer is on the drive side only, so the crank can't be centered on the frame. Score an extra spacer from Shimano, grind both spacers down to 3mm or so and place one on each side of the BB and your centered. But here is the kicker. The M771 spider is different and deeper, and the rings are 26, 36, 48. By recentering the 3mm spacers the chainline changes inward from a 50mm to a 47mm, which in my opinion is better suited to the 1 x 10 setup. Also you have the option to keep the 36 middle or go to a 2 x 10 and run the 26, 36. This is an outstanding gear ratio for a 29er.
Good Luck.