What do you think the best train is? The best steam train? The best electric train? The best diesel train?
I think the Mag-lev TVX-1 is the best train. I also think it is the best electric train (duh!). As for the best steam train, I think the DB 18 201 is the best with only 1 downfall, the cost and the late-game ability. I don't use diesel so I don't have an opinion there.