Finnair feels like it's less likely to go bankrupt?

lol, would be a shame to switch and end up in the next insolvency :)

Iberia is profitable and third largest airline group in Europe (after Lufthansa and Ryanair). That said, Finnair is also profitable, which is #17 in Europe.

For which one to pick, I'd pick the one you're more likely to fly with. I've flown both intercontinental in economy, and enjoyed Finnair better. However, not knowing much about your travel behaviour, my bet would be that the most likely you're going to fly with out of oneworld's European airlines is probably BA, in which case I'd go for Iberia, as it's the same loyalty program.

Actually, I'd sign up for both. Also, don't know your travel behaviour, but I'd try to get a status match outside of oneworld, as airberlin's routes probably won't be replaced by another oneworld airline. And layovers in LHR suck. http://statusmatcher.com/airlines might help.

Also note that Finnair seems to give a status challenge for Gold: http://statusmatcher.com/report/56885

Status-matching outside of oneworld is nigh impossible with topbonus, unfortunately.

Signing up for both is kinda useless as you can only collect miles/points on one number per flight, no? So I think you should have a plan where to collect. The Finnair challenge is pretty easy actually, and might actually make more sense, if you start with 0 points on Iberia, and they reset the status in April (apparently they count April-March for everyone).

Platinum can be matched to *G on Turkish, Gold by Avianca Brazil, or with a challenge on Air Canada or United. Or by Lufthansa when signing up for M&M with an Italian address. Might be helpful if you'd be switching to mostly Lufthansa Group.

Thanks! That's very helpful information.