The Polaris seat is pretty good if you can get one of the odd-numbered windows (flying solo) or odd-numbered pairs (flying as couple). If you get an even, it's not as good. The UA 752 is to be avoided if possible IMO. The pitch and the footwells (except for the bulkhead) are very tight, and of course not all direct-aisle access.

UA service is highly variable but tends IME to be a bit worse than average compared to other full service carriers. The food ranges from abysmal to passable. If the schedule and fare are right, the 772 option is worth considering.