Anyone know major differences between United Airline (UA) vs Air Canada (AC)

I am debating between flying between following two airlines from (EWR>SFO>SYD) to Sydney (EWR>YVR>SYD). I have UA card, miles, etc. and although UA is not terrible, but have heard some great stories about other flights (e.g., Emirates; though it's not flown to SYD). Figured I give another airline a try such as Air Canada. I will not fly China/Asian airlines. Therefore between UA & AC.. how are the following if anyone has flown both:

• Liquor
• Food
• Seating (leg room, cleaniness of seats, roomy)
• Newer Plane

Have liked and flown:

• Virgin

Don't like the following:

• Air India
• Lufthansa