You need to tell us what matters to you. For example, are you mostly interested in elite status, award redemptions, etc.? Then, what class do you usually fly in (ie: Y, C, or F)? Depending on your needs, the answer may be different.
LAX
(1) My home airport is WAW but later YVR and WAW
(2) I usually buy Y fares (mostly 50% of Y Economy)
(3) Really, it depends, i dont know, but I always fly on transcontinental flights
(4) I am Vietnam Airlines' Gold Skyteam Elite
(5) The most important to me in a FFP are airport lounges, pick-up luggage earlier, Priority Check-in, easy free upgread to a better class (like in VN)
(6) I mostly fly like WAW-HAN-WAW
(7) My preferred airlines are LOT, Singapore Airlines, Vietnam Airlines (SKT).
(8) Mostly for pleasure.