Thanks, Ian – I think that is a very fair summary. As you say, choice of alliance will depend on geography and personal preferences but the objective information provided here is useful.
One minor addition, not really covered here, is lounge access on partner domestic flights. This does seem to vary by alliance or maybe by airline. To illustrate, I have top tier status with oneworld (BA) and skyteam (KLM). Flying domestic economy with Qantas gives me lounge access in Australia, using my BA card – I also think that oneworld top tier flyers have access to BA lounges in the UK when travelling economy on domestic flights. However, flying domestic economy with Vietnam Airlines does not give me equivalent benefits via Skyteam, as I reconfirmed during recent travels. I also think that domestic lounge access does apply with Star but my experience is limited – I certainly used the TK domestic lounge last year, when flying Istanbul – Ankara and vice versa, based on my (then) Aegean Gold Card.