Yep, when you're VIE-based and do the most of your business flying on AB from there, topbonus would be the logical choice.

Personally, ever since since AirBerlin joined oneworld, I credit (almost) all my AB flight activity to AAdvantage. The vast bulk of my accrued mileage is done flying TATL on OW airlines and domestic connections inside the US, so that was the natural option for me. I don't fly enough intra-european to maintain status on AB separately.
By pooling all activity into one program, I am usually able to get to OW Sapphire status any given year, which gives me lounge access (very helpful for those long LHR layovers connecting from flying BA out of BSL to LAX on AA), free seat selection including the all-important ability to pre-reserve XL seats/exit rows on AB free of charge, which is a real tangible benefit as well as having complimentary access to MCE (AA's version of "premium economy" with more legroom) on AA as well as earning 'sticker upgrades' for upgrading my US domestic flights.
In general, which oneworld FFP program(s) you choose depends on your flying habits and personal preference. My focus lies on the other side of the Atlantic, yours probably in Europe or Asia.
Seeing that AB and EY are in bed together as tightly as they are, I'd check out the EY program as well. When flying to Asia out of VIE, you probably end up on their planes a lot.

The topbonus program has been aligned with the rest of the OW benefits when AB joined OW.

check out the benefits of the three levels on the OW page: http://www.oneworld.com/ffp/

Topbonus does have a few advantages (that's why I continue to use it occasionally):
- some discount economy fare classes earn only 25% miles on Aadvantage, but 100% on topbonus - it'd be a waste to credit those flights to AA. When you fly AB a lot, and you or your employer buys discount eco fares, this is important (same situation as with your Finnair flight above)
table here.

- companion ticket: When you have a significant other and want to use your miles for trips with same, you get the second award ticket for half the miles.

- AB has "Schnäppchentickets" on offer for redeeming miles which are a very good value. Those are for topbonus customers only.

- Additionally, topbonus offers the option to redeem additional miles to cover the cash-co-pay-required-everywhere-else taxes and fees which can be pretty costly on some destinations like the UK or CDG...
And their redemption rates are pretty good - 40k miles for a business class flight to the US compared to 50k for AAdvantage. Availability of awards is good as well, too.

I'd go with them.