AS F Pros:
Boardroom access
Better CS
F>>>E on AS
Beer selection beats UA
Reasonable alternatives if flights to LAX are severely delayed/cx'd
Cons:
Seats are lousy
Those strange religiously themed cards they give you with meals

UA F Pros:
Better Seats
F>E+>>>E
Better IFE

UA F Cons:
Comparable tickets are more expensive on UA vs AS
Random UA rules and FAs
Fewer flights to the LA Basin