I ride daily on mixed surfaces that include about half single track with lots of roots and some ruts. There is also some nice packed sand "gravel" riding and some pavement to get to and from there. I find a 29er hardtail MTB to be pretty much ideal for that. I might some ride my old rigid MTB if the roots weren't so numerous and harsh. I do ride it now and then if I ride different trails than usual. There are plenty of options nearby that suit it and would also suit a nice new gravel bike.
I tour on road and on mixed surfaces, but don't like touring bikes much. I enjoyed riding the southern tier on my old 1990 cannondale crit bike packing uktralight camping gear. I have also done ul touring on mixed on/off road on the rigid MTB. Both worked out really well, but I'd consider a gravel bike for all but the most technical off road if buying something new.