To answer the original question by OP on chance of upgrade, the PE to J upgrades are processed before Y to J as that opens up a Y to PE upgrade slot
So you will be before all WP in Y requesting upgrade, making the odds close to 100% if the J seats are empty enough (as they are on most dates/routes these days). AY is great value for J and does also offer an aournd-the-world fare (not OWE) that is pretty good. Some of the other choices mentioned such as Air China are problematic and ones that I personally would never buy, but to each their own evaluation.