United's new bedding, plus the generally comfortable nature of their lie flat seats, may make Polaris the most cozy J seating out there.

I'm just back from a TPAC with AC J, and found Polaris seating (747 UD) more comfortable. The only drawback with Polaris in the current fleet is lack of exclusive aisle access on certain aircraft - like the sUA 777s and 747.
UA's wines and spirits were better than AC's too, btw.