Also finding award flight with Finnair Adios might be a challenge. The booking engine doesnt recognize first class.
So options are finding free award from another airline or EF, calling AY and hoping that seat is released to AY also. Ofcourse nowdays you can move Adios around to BA and QR, but specifically with AY Adios, its not easy.

From part experience, part reviews i would rank the Oneworld first class as following (YMMV):
JL, solid product even on the older seats. Salon is a great champagne (try to depart ex-HND).
CX, taken a slight turn down still pretty solid. Will get better with new suites whenever they will come.
QR, honestly, QR first is not that much up from their J product. Al Safwa has seen many enhancements also.
BA, inflight is nothing to write home about. If you end up spending money or points on this, better to include LHR as starting point so you can enjoy Concorde Room as it will save some of the "first class glamour".
QF, never flown or not too many reviews around. Probably better than BA.