Poly - Longevity, Comfort, Spin...in that order
I've tried to ween myself off poly b/c I string myself and its a bit of a pain vs multis and goes dead relatively fast so I have to do it more often. I just can't seem to give up the spin. Pretty much any poly will give me enough spin vs other string types so my priorities are:
Longevity (not wear but deadness), comfort and spin in that order.