Thank you both for your kind help.

If I could reach e.g. BAEC silver level within one year, in order to gain access to lounge etc, why would this be preferable to Finnair Plus? I'm just a little bit at a loss at how to compare them. It seems to me that Finnair Plus is the easier option, but I'm also a beginner with comparing the different programs and perhaps there are aspects I haven't considered. By using the BAEC calculator it seems I will get 90 tier points per flight ARN-PVG and back. This would mean I would need some 7 return flights to Shanghai each year. This however doesn't take into consideration that I would also need 4 eligible BA flights (or Iberia) something which I can't say for certain I would use at the moment.

Using the Finnair point system, it seems I would need 5 return flights in "Value" Economy to reach AY+ gold membership. This seems to be the same as BAEC silver, but looks like it's easier to reach (although often "Value" is more quite a bit more expensive than "Basic", which is only half value).

It seems to me I should be sticking with AY, but maybe I'm missing something.