For Tenere:
Guranteed to never let you down.
Will go through and over anything in its way.
Full tank will take you to the moon.
Brakes good even without ABS.
Easy to move around in car parks etc.
Easy home servicing and cleaning.
Cheap parts readily available on ebay and the like.
No expensive throttle bodies to balance or shims to replace when doing tappets that main dealers bankrupt you for.
Happy going to local shops as it is going to Morroco.
Cruise at 75 to 80 mph easily all day which is more than sufficient for most.
Cheap insurance.
Gets under your skin and becomes part of you.

Against Tenere:
Very high to mount and disembark.
Not so smooth as most twins/4cylinders.
Seat can be hard on long trips.
Obviously not same power output but 80mph cruising is more than sufficient for most.
Typical big single thumper vibes and heavy engine breaking on chain/rear wheel.

A lot of these things are improvable though with a few mods.