There are two separate issues here: which is the best airline, and which is the best programme.

Where are you moving to?

Where do you tend to fly?

Alaska Airlines is not part of OneWorld but it has lots of OneWorld partners, as well as Emirates, KLM, Singapore Airlines, etc. Earnings are generous, as are mid tier benefits (top tier less great), and fees are sensible.

You can't transfer points but you can spend the avios on a different airline.