This is hard for me since I have many of the ones listed. Altough they are ones for the business and ones I will eventually part with.
For a long term keeper I would say I would seek out an amnestity registered M1A1, M1928, 1928A1, BAR or 1919 with true provenace of WWII history. Something that has seen "the whites of their eyes" in either Europe or the Pacific Islands.
Hasnt been said yet, but I'd take a Saiga 12 in full-auto. AA-12 are just hidious to me, and theres something about a full auto 12 gauge that just gets me goin