As a long time smoker in an area where the lineage of the weed was more a result of the sellers imagination than fact, I have limited experience with any "real" strains (other than what I have grown).
I'd have to go for the polar extremes - a mind snappin' sativa, and a narcotic indica.
Haze? and LUI?
Cross the hell outta 'em, and harvest early, on time and late.
Zamal x Neville's Haze and Colombian Gold, happy to have nothing else if I oculd grow those two under the tropical sun, make some huge trees of sativa goodness.
If stranded on an island (per the first post on this thread) I'd go with a Thai Sativa and a Paki or Hindu indica. Isn't that how DJ made Blueberries? The reason I'd do that is to get both seedy time and time again, put the beans a a coconut and dig them up underground in a safe place so I could make protien shakes with the beans and grow them (they wouldnt go stale so fast if kept cool is my understanding).
But first I'd need a hot lady to keep me company.... then we could talk meds...
I think I'd be with those who would choose a couple f1 hydrid, or poly hybrids, as that would give you the best opportunity to breed further, and create a diverse group of plants from the original 2..
I think I would go with maybe a
Mothers Finest x sweettooth
Chemdog d / sour diesel ibl x f13
I'm sure you'd get a ton of variety from each of these hybrids, and with the different flavors involved, and overall descent potency of the parent strains you'd probably put some killer lines together in no time.