haven't try these airlines.
but it seems TAP not much difference from IB in terms of quality.
so it depends on if you really need those OW miles to re-qualify this year, i guess.

if i were you.
1. TAP if enough for EXPLT (i guess u are starting AONE6 there?)
2. BA if the flight is empty
3. IB if the flight is full
these are one-way, right?

i suppose you already exhausted the means of ex-ARN options, such as AY, mileage award, etc.

i myself have the similar dilemma, for HKG-JNB.
1. CX Y award 1-way for 28k miles (they are running 30% discount for Y in asiamiles)
2. CX oneway J for 60k
3. CX RT J for 100k (but it might be just over 12 month when i come back, or i may not even take the last hkg-jnb leg)
4. purchased fares are all RT, and very expensive in both J & Y