I have created tire pairings based on personal testing and use on our dry hardpack and loose over hard technical terrain. These are pairings that I consider "smart", tried and true real world tested by a veteran mtn biker. Many of them use a staggered F/R sizing practice. If that is not your practice, you can always size up the rear. The following commentary will help you decide if this pairing is right for you. See the "more ads by this user" link above this text to see other pairings and parts.
Rear: Vittoria Morsa 2.35 Trail. 4G Isotech+ compound with Graphene. This stuff is fast! Like a semi-slick except it has more traction, which our faces appreciate. Measures 2.35-2.40". 800-850g fast, hybrid square profile tire that promises 2 things: speed and decent cornering. The short center knob, paddle shaped tread insures better than average straight line climbing as well as braking traction. With large side knobs, it does not disappoint in turning traction like most race tires do. $59
Front: Same tire. $59 If you want more volume, size up to the 2.6 for $10.
Combo Savings $99 for both for 27.5, $115 for 29"
This tire stays under the radar as one of the very best . As a combination, this is blazing fast, with average sidewall protection (though better than an exo Ikon, for example). Race worthy for courses where you expect to climb and descend, but don't need the penetration resistance of 2-ply tires.. For heavier riders, not advised for descending black steep technical. Remember also, while this has a hard compound, the rear tire is going to wear out quickly if you are on a lot of vertical. You can have fast, or longevity...you can't have both. Still, most riders will find the lifespan more than acceptable.