***Update: please note the below percentages are a rough guide and based on out-of-date / inaccurate info. (See subsequent responses for clarifications re. AY, for example)

Thanks for all the great input so far.

Interesting answer below from Claude AI, though not sure how accurate it is. I asked it how close (in percentage) a given return flight on each OW FFP takes you towards Sapphire/Emerald.

N.B., for simplicity, I asked it to assume BA metal originating from LHR in each example.
Also, the BAEC example is the old TP system - included only for reference.

STATUS THRESHOLDS:
* Old BAEC: 600TP Sapphire (Silver), 1500TP Emerald (Gold)
* Finnair: 42,000km Sapphire (Platinum), 90,000km Emerald (Platinum Lumo)
* American: 75,000LP Sapphire (Platinum Pro), 125,000LP Emerald (Executive Platinum)
* Alaska: 40,000mi Sapphire (MVP Gold), 75,000mi Emerald (MVP Gold 75K)
* Qatar: 50,000mi Sapphire (Platinum), 100,000mi Emerald (Platinum Privilege)
* Malaysia: 40,000mi Sapphire (Enrich Gold), 80,000mi Emerald (Enrich Platinum)

LHR-JFK Business Class (~6,900 miles/11,100km RT):
* Old BAEC: 140TP (23% to Sapphire, 9% to Emerald)
* Finnair: 11,100km + 25% base bonus = 13,875km (33% to Sapphire, 15% to Emerald)
* American: 15,000LP (includes cabin bonus) (20% to Sapphire, 12% to Emerald)
* Alaska: 6,900mi + 50% cabin bonus = 10,350mi (26% to Sapphire, 14% to Emerald)
* Qatar: 6,900mi + 25% cabin bonus = 8,625mi (17% to Sapphire, 9% to Emerald)
* Malaysia: 6,900mi + 25% cabin bonus = 8,625mi (22% to Sapphire, 11% to Emerald)

LHR-CDG Business Class (~400 miles/640km RT):
* Old BAEC: 40TP (6.7% to Sapphire, 2.7% to Emerald)
* Finnair: 640km + 25% base bonus = 800km (1.9% to Sapphire, 0.9% to Emerald)
* American: 3,000LP (includes cabin bonus) (4% to Sapphire, 2.4% to Emerald)
* Alaska: 400mi + 50% cabin bonus = 600mi (1.5% to Sapphire, 0.8% to Emerald)
* Qatar: 400mi + 25% cabin bonus = 500mi (1% to Sapphire, 0.5% to Emerald)
* Malaysia: 400mi + 25% cabin bonus = 500mi (1.3% to Sapphire, 0.6% to Emerald)