If people are making a gargantuan request list, here are mine as I pre-order the gargantuans from my FLGS and pick up minis as needed:
Tyrannosaurus (It indeed would be cool not to have to use a toy.)
Elementals (The four basic types)
Linnorm (Any type would be good, or just a general one.)
Carnivorous Blob (I know it's normally bigger, but a gargantuan one with stuff in it like the recently released cube would be awesome.)
Ravener
Warsworn (I think Wizkids could make a great pose out of it.)
Quanitum Golem (Inner Sea Bestiary, perhaps too niche.)
Megaprimatus Ape (Again, it would be cool not to use a toy, but I get why this would not necessarily not make it.)
Devastator
Wyrmwraith