You need to add a bit more info. Are these P-class tickets, J-class tickets. Spent per ticket.

If you want *A, irop protection and ticket flexibility and you are buying more expensive J tickets then definitely UA - they have the most flexible ticketing policies and you earn well on UA-issued tickets in J. Now, if you have EU-South America via say LH/LX - you can't ticket that on UA ... so tell us more about your usual travel