That's a tough choice. <br /><br />If distance were not an issue, I'd pick Neptune first, for four reasons:<br /><br />1.) Triton's gravity would make orbital maneuvers easy, while Uranus has no massive moons.<br /><br />2.) Triton is a fascinating moon in its own right, with cryovolcanism, a substantial atmosphere, and an otherwise active dynamic. <br /><br />3.) Neptune's ring arcs are a great mystery, that I think that only a dedicated orbiter will be able to solve.<br /><br />4.) Neptune seems to have a much more vigorous atmosphere than Uranus.<br /><br />However, Uranus has its pluses, too:<br /><br />1.) How it got its axial tilt is another one of the Solar System's great mysteries.<br /><br />2.) Though Uranus has no large moons, the five largest each have a distinct geology, something that could tell us a lot about comparative planetology.<br /><br />3.) It would be fascinating to study the effects--if any--that Uranus's long seasons have on its atmospheric circulation.<br /><br />4.) Its axial inclination would present a number of difficulties for a mission, but it would also expose previously unseen parts of the system to view, over much shorter periods than would be the case at Neptune.
Facebook
Twitter
Instagram