I’m currently running Conti Cross Kings on rear, XR4 on front. I’ve found this to be a versatile combo - good for Colorado mountains and Moab.
They’re both pretty light tires however - closer to the XC end of trail tires. So if you like to plow through rough stuff, you may want something beefier.
There’s a lot of possible combinations that could work however. It’s a question of trying different options to see what you like.
You just have to look at the combinations specced on popular trail bikes - see below for a few examples. All are different.
Bike: front, rear
Fuel: XR4 2.6 F and R
Stump jumper: butcher, purgatory
SB130: Minion DHF 2.5, Aggressor 2.3
Ripely: Hans Dampf, Nobby Nic
Tall boy: Minion DHF 2.3, Minion DHR II 2.3
Transition Spur: Dissector, Rekon
Giant Trance: Minion DHF 2.5, Dissector