If you could onyl visit 1 pub in Budapest, that should be Szimpla Kert. The place is a ruin-pub, which is already an original establishment (you can only (or mainly) find these kind of places in Berlin and in Budapest). The place has indoor and outdoor areas with unique design and murals. In the outdoor area sometimes there is live music or they screen movies as well. Also, in the weekends there is a farmer's market. Wide selection of drinks and snacks as well.