Budapest!
I stayed in Budapest for 2 weeks. It is one of my favorite places. The river, sights, food and nightlife are amazing. During my stay, I overnighted in 3 different hostels. When you arrive in the train station, I wouldnt recommend you take the hostel that the man with the sign is offering. I arrived and I was the only one there, in this two bed apartment.
I ran out of money while in Budapest, and was still able to make it. So is not to expensive.
I would recommend Budapest to anyone!