IMO, Vybe Deluxe can't be beat. I guess it depends on what you intend to feed it. I say Vybe because I can feed it massive amounts of OD/Dist/Fuzz as well as huge reverb, delay, modulation, straight in front of it, and it handles it all remarkably well, almost as if the fx are in a loop... If I could have only one module, that'd be it.
Other good pedal platforms are stock clean & blackface, clean 'channel' of the stonerverb, plexi side of a mash-all or JF XTC, and even my 50R is a great platform with the gain at noon or lower.