I haven’t explored Cathay specifically but I have participated in a few Oneworld programs (QR, BA).

From a points perspective, I think I have better luck on AC. I’ve generally found better redemptions, earn points faster. And things like priority rewards are super helpful. But definitely *A redemptions are way harder now than before.

I haven’t really managed to find many great long haul J redemptions on OW and feel like I earn points more slowly.

From a product perspective I much prefer OW; although this is biased due to my travel patterns. I mostly fly on Qatar these days & also love the new Finnair seat. First class lounge access with OW Emerald is a great benefit. And, on a few occasions, I’ve gotten OpUps to First on Qatar which is a great treat.

Also highly anecdotal, but I’ve found the price point on OW for J to be pretty reasonable, so these days I’ve just been buying J instead of chasing redemptions. Versus AC’s crazy price point for a mid range product.

Because of that I’ve actually found a good sweet spot where I use my OW points to get free short/medium haul flights (where there’s a ton of availability) and pay for long haul J.

Finally I haven’t been able to find an airline outside of North America with a meaningful way to get free upgrades. Pretty consistently I see these other airlines offer one long haul upgrade per year, whereas with AC I can get several per year. So if upgrades are important to you I would advise staying with a North American airline.

All of this may be highly dependent on my situation and travel patterns, since I live in Europe now and often fly to places where a connection in e.g. Doha is convenient. My answer may have been very different if I was l still living in Canada or travelled to different destinations.