Plat Pro here, after 10+ years as an EXP. I refuse to play the credit card game. Based in CGK, I buy QR J fares to get back to the States. Once in States, rarely would I step on an AA flight, I just buy what is convenient. DL seems to work best for me. I credit my QR/AA codeshare flights to AA bc I like the program, and I can easily hit Plat Pro. Being a one world emerald is what is important to me.