The only country in Europe which has any following in American football is Germany. Elsewhere Rugby Union is absolutely dominant. Russia, for example has it's own professional domestic league. So does Spain with it's "Super Iberian" League. Romania and Georgia send a lot of players to French clubs and can field reasonablly strong national sides. And pretty much every nation in Europe participates at some level of the European Nations Cup competition.
In Poland rugby is more popular.
I would expect Rugby but neither are especially popular.
Rugby.