I love Slavic languages! Polish, Ukrainian, Serbian, and Russian are the ones I'd like to learn the most. Polish especially- as it relates heavily to my historical interests, and learning it would be very beneficial. I'm currently taking a Russian course at my university, and doing pretty well in it, because my previous attempt at learning Polish has really gotten me used to how Slavic languages work.
I'm also interested in Basque, Ainu, and Wymysorys, as well as the Texan dialects of German and Silesian, although finding proper, high-quality resources to learn these languages would likely be near impossible.
Annnnnnd finally- Italian. Just because it sounds pretty and I wanted to learn it when I was a child, lol