On my LHT I use Panaracer RiBMo's (26*1.5" 80psi). So far great flat protection and not that bad of a ride quality. It originally came with WTB Slickasaurus tires. Rolled really well, but poor flat protection.

On my hardtail I have Specialized FatBoys (26*1.25 100psi). Very fast tire however flat protection was so-so at first, but has gotten better. Originally put Michelin transworld Citys on them, but didn't like their heavy feeling on the bike.

On my rigid I have Specialized Nimbus (26*1.5 80psi). It has ok flat protection and ok ride quality.