well, as you said "i cannot choose the airline and its primarily business" you basically are stuck with whatever airline or alliance your employer uses for your business travel. Having or attaining status on the carrier you use most is the logical thing to do. Once-a-month TATL or TPAC will get you there pretty quick.

As far as OW programs go, be aware that Finnair Plus has lousy earn rates for anything less than full fare classes. Discount fares in Y earn only 25% or 50%, so not recommendable unless you buy V and above fares (details). AAdvantage is much better in that regard - you get 100% mileage credit on even the lowest fares.