I'm 150 lbs, ride fairly clean lines, like to carve my turns riding the edge knobs. I prefer squarish profile over round profile. Favorite 26" tires are Kenda Nevegal 1.95, 2.1 and 2.35; Maxxis Minion F/R in the "freeride" casing 2.35.
I ride an On-One Inbred fully rigid. Rims are WTB Laser Disc Trail 29. Also have spent time riding a Turner Suiltan with same rims. Rim width matters on tire profile. The original On-One Reetard rims were narrower than the WTB rims I'm using now, and the Nevegals and Rampages are much rounder in profile on the narrower On-One rim. I like the profile better with the WTB rim under them.
I tend to run about 30-32 psi front, 30-34 psi rear. Some tires are more sensitive to this point, especially the really thin-sidewall tires like the Maxxis Ignitor. On that tire I have to run at least 33 psi in the rear or it will roll off the rim if below 30 psi and squirm like crazy between 30 and 33 psi. Nevegals and Rampages are more flexible on the psi, you don't get the same weak squirminess. Same with WTB ExiWolf which has good sidewalls and is tall, so it tolerates lower psi.
29" tire combos:
For rocky, rooty, rutty technical: Panaracer Rampage rear, Kenda Nevegal front. Nevegal is stickier and slower, better up front. I've ridden Nevegal front/rear and the speed / rolling resistance difference between a Nevegal and a Rampage is pretty significant. The nominal size difference is irrelevant on my rims.
For hardpack: WTB NanoRaptor rear, ExiWolf front.
Hardpack w/ loose (grainy, sandy) surface: WTB ExiWolf rear, Kenda Nevegal or Panaracer Rampage front.
Loose small rocks over hardpack: Maxxis Ignitor rear, Kenda Nevegal front.