the zero jacket has a heavier and thicker insulation than the mont bell parka so I think the zero will be warmer by far. but it really depends on what you are using it for and what other clothing you are wearing. because if you dont need the extra warmth you doont need the extra weight
ZERO JACKETâ„¢
U.L.Thermawrap Parka
loft summary
mont bell parka: 80g exeloft
OR zero: 133 g torso, 100 g sleeves, 60 g hood primaloft one
for a comparison of the mont bell and a patigonia micro puff see this link
Comparison