I am in a similar situation - so I looked up the Finnair program and that looked quite good to me but perhaps I am missing something. Previously a friend had extolled a lot on the LAN Chile scheme (but that was a few years ago).
Right now I don't want award flights because I can fly for free (expat. package for holidays, and paid business trips). I don't care about lounge access, and I won't be earning on a credit card.
I would like to accumulate points/miles for a rainy day or, better still, to get preferential seating/upgrades, or at least some non-flight award so that I don't feel I am missing out.
For me the BA Exec Club was poor because you don't keep the miles when you transfer between certain countries (e.g. in my case Japan to China) and I believe my children were not eligible for accounts. I also fly as little as possible so don't accumulate that fast so expiry periods are important. However, BA is the One World airline I am most often flying on.

I expect to be relocated somewhere else next year (no idea where) but also expect a long-term interest in flying between China and the UK and if doing that on my own budget might be looking at cheaper indirect flights. Helsinki seems like a reasonably good route to take.

So looking at Finnair: the plus points seem to be 5 year point lifetime, acceptance of children 2-17 years, efficient website.

Looking further ahead - I am going to prefer to fly on new generation planes which maintain a higher cabin pressure. That is going to mean the Boeing 787 or (I hope) the A350 - I see Finnair are an early customer of the latter.