OP not sure if you are looking at JFK or EWR, CX flies from both. My responses, and a letter grade, are below:
Lounges (CX A- (ex JFK), B+ (ex EWR), UA D)
at JFK you get the AA FC lounge, at EWR you get the BA lounge. Both are vastly better than the crappy UC club at EWR.
at HKG the CX lounge is great, makes the UC club look like a low grade slum (and it is actually not bad for a UC).
Seat: (CX B+, UA C-)
UA has non-direct aisle access 2-2-2 seating ex-EWR. Seats are last gen, 78" of pitch, little storage space.
cx direct aisle access 82" long, harringbone, lots of storage/space.
Drinks (CX B+, UA D)
UA has random wines that cost about $12-15 retail.
No espresso drinks. ETOH is not great
CX has wines that cost about $25-30 retail, espresso drinks, better booze, port.
Food (CX B-, UA C-)
CX's food has gone down hill, but is still better than what UA serves. If you like Texas cafateria style food, UA is for you.
In flight sevice (CX A-, UA C-)
I have always found CX crew to be helpful and attentive, but not stuffy like the SQ/JAL/ANA service. UA, some great helpful crews, but you also may get someone who thinks they work for a diner, slopping down food before going to read a magazine. YMMV.
No one in their right minds would say take UA. The only reason to take UA is (a) you have a corporate deal with them so its a lot cheaper, or (b) you are trying to retain GS or hit some level in UA's program.