Also, especially seeing Helsinki and Asian cities is on your list of destinations: Finnair. Mostly distance-based with no spend requirement, although they have changed to fixed points accrual on their own flights, points don't expire as long as there's account activity once every 18 months, getting to OW Sapphire isn't too hard with them especially when you use them to fly to Asia from North America in a premium cabin
And they're a nice airline to fly on. No premium economy, though. Downside: Heavily discounted business class fares (what I buy...) have been devalued and aren't earning as well as they used to on their own flights. Those cheap QR business fares still earn well, though. And their award charts are not that attractive with the exception of OW RTW awards.
Status tier accrual is annual but starts and resets on the join date, not Jan. 1. They partner with Capital One (you can transfer points to Finnair)