Last year, there was a decent BA Business Class deal passage from Prague to San Francisco (via London Heathrow) for £1,178 Return.

If you credited those flights to British Airways Executive Club, you would wind up with about 18,000 Avios, worth about £180.

If you credited similar flights to The Frozen North Mileage Plan instead, you'd wind up with around 30,000 Gold Country Miles, worth about £500.

Both airline programs credit Avios/Miles based on how far you fly, so the precise model doesn't exactly make any difference - as a ratio, the difference in earnings will remain something similar.