The ubiquitous Pentax Spotmatic. Everyone I know personally that is still in photography seems to have started with a Spotmatic, and many still own their first one. Indeed I still have mine, I'd get so little for the thing it hardly makes sense to consider selling it.
I bought the camera in 1966 but have barely used it in the last 30 years. I still have it and it seems to function as well as the day I bought it. The meter even corresponds correctly when compared to my F3HP.
As for quality; just holding one of these cameras speaks volumes. I'd put the body quality up their with the Leica M stuff any day. The lenses, even though well built, are likely a little soft but I've never noticed this.
I think the Spotmatics are worth far more than the market value, which seems to place more on rarity than quality sometimes.
Tell him to hang onto the camera.