The real ethical question here is, is there only one round of trolleys?

Because if this is a one and done question, then obviously I go for the one person.

But if it’s possible at any point somebody comes along and has to run the experiment again after me, then if I leave an infinitely expanding number on one side, all it would take is one sadistic person to wipe out a incalculable amount of life.

In which case, I take the track with two people. And again, it is a question of repetition whether or not doing it once means that it won’t happen next time or if this will continue with every cycle.