I take my firearms collecting from a longevity and utilitarian point of view, and I want the best bang for my buck, so here's my thoughts:
PTR91 - Current production. CHEAP mags. Tough as nails. Current production PTR's have quality modern factory optics mounting solutions. Spare parts being made and available surplused (if you ever need them). My choice pick out of the group.
M1A- Quality forged versions are expensive. Mags are expensive. Spare surplus quality parts are getting thin, aftermarket mostly. Takes extra to mount a scope and accurize if not done already from the factory.
AR180 - "Orphan" firearm. Good luck getting spare parts. Magazines are expensive and exclusive to the platform. I'm not aware of much aftermarket support for the platform.
JRC 9mm - A lot of money for a pistol caliber platform that's the size of a rifle. The mag interchangeability is nice. Great if you're looking for something to interface with your pistol as a truck gun.
VZ2008 - Cheap (right now). Spare parts will dry up, but seem easy enough to find if you dig for a parts kit. Magazines are exclusive to the platform, but relatively affordable (for now). Aftermarket support is so-so, and I have no idea if there are even optic mounts made for it. On the plus side, they are still being allowed for importation by CZ (for now, although expensive compared to the Century version).