Having flown both a fair amount I'd give AC the edge - signature lounge slightly better than Polaris (you have to queue to get in but when they let you in they find you a place, in the restaurant, bar eating area or lounge depending on your preference; Signature seat is roomier but as noted by others, tray table placement isn't optimal (but didn't really bother me); equally easy to sleep in either for me; AC food on board coursed and better overall