I'd never do a budget carrier in such a long flight. Even if Finnair has cheapened themselves like SAS did (don't know, never flown them) then I'd still take them over an actual budget carrier.
Mileage program is a big influence for myself on which carrier I choose, so personally I'd pay a bit more for a full service Star Alliance carrier. Finnair is OneWorld if you're using one of their programs, but OneWorld has a lot of non-earning fares on budget tickets so wouldn't count on earning much anyway.