Funny, when I started this tread I was thinking SVTU and Ms Marvel were at the top of the list, but thinking it over, only Ms Marvel makes the top in term of popularity.
And looking back to SVTU, Woof! there is some seriously mediocre material in there, the real value in SVTU were the 2 main characters, Sub-mariner and Dr Doom plus the 
crossovers.
If I were to draw any conclusion from this tread it would be this, there is really very little 70s material that is actually viable as a reprint.
If we get lucky this is what I think might happen:
Ms Marvel as TPB
SVTU can go any way because of the big name characters, it could be done as TPB, Omnibus including Dr Doom, or even as MM after Subby MM line is completed.
Killraven only an Omnibus could get this line completely reprinted, a TPB line would die after the 2 volume.
70s Horror lines,  I see them all as poor to marginal sellers, at best, again Omnibus would be the way to go.
Copyrighted material..... wake me up when it happens, if ever,  yes I think it is that unlikely.