The choice is between three parties: the True Finns, described as Finland's equivalent of the Sweden Democrats, the National Coalition Party, or Finland's Moderates, and the Social Democrats.
"The True Finns are odds-on favourites when it comes to becoming the largest party," says Thomas Karv, doctor of political science at Åbo Akademi University in Vaasa and senior lecturer in political science at Mid Sweden University in Sundsvall.
Deep collaboration
Looking at opinion poll figures, however, it weighs in favor of the Coalition Party. How it ends, we know at best late Sunday night.
"For Sweden, it doesn't matter so much which party wins. The countries already have such deep channels of cooperation, so it will not be noticeable more than perhaps a small difference in nuance in Sweden, says Thomas Karv.
"When it comes to defence and NATO, Sweden and Finland already have close cooperation, and all Finnish parties strongly agree to cooperate with Sweden in defence policy. The other issues are often decided at EU level.
Several of the party leaders on both sides of the Baltic Sea are already well acquainted with each other – even across the bloc boundaries.
"Kristersson has a good relationship with the National Coalition Party's Petteri Orpo. If Finland were to be led by a right-wing bloc, it could further promote and deepen cooperation. But Kristersson also has a good relationship with the Social Democrats' Sanna Marin," says Thomas Karv.
"They are openly critical of the EU"
One possible scenario that could lead to cooperation problems is if the True Finns are given a lot of say.
"They are openly critical of the EU and want Finland to leave the EU in the long term. On the other hand, they depend on the National Coalition Party for power, and they are the most pro-European party in Finland.
"Whatever happens, Finns will continue to come to Sweden as tourists and workers, and Swedes will be just as welcome in Finland, regardless of who wins.