My universal favorite is Viljamovka, but I had amazing Kajsija rakija in Bjeljina, and the best homemade Kruška rakija from a pijaca in Mostar.
There's a šljiva that's made in Prijedor that is also pretty freaking good.
When I was in Neum, they kept buying me travarica, but it's not for me. It got me really drunk though:D