Based on connection times and number of flights Finnair should be your best bet. Also, if you're planning to earn AA miles, you get them from all the Finnair flights. BA transatlantic flights don't earn AA miles and not sure Swiss ZRH-MOW mile earning option. However, if you are planning to travel in F class, Finnair doesn't have one. HEL as a connection airport is definitely the best choice. Hope this helps!