Personally, I would really love to go to Titan. The methane oceans and thick atmosphere seem really interesting!

But many of the other bodies just in our Solar System are super cool too. Venus is a hot destination, I would love to visit Ceres, the queen of the asteroids, and many of the icy moons would be fun to explore too (think Europa, Callisto, Ganymede, Enceladus, Titania, Triton…)