The Uranunian system has five objects that could potentially be colonized: Miranda, Ariel, Umbriel, Titania, and Oberon. Uranus also features the particularly large yet irregular shaped moon, Puck.
Miranda[]
At 293 miles in diamter, Miranda is the second small
From left to right: Puck, Miranda, Ariel, Umbriel, Titania and Oberon
est object known to be spherical in nature (only Mimas is smaller). The surface is a mis-matched patchwork of different terrains, making the moon look like it was broken apart and then coalesced several times. The surface gravity is only about 0.81% Earth's, making it an unlikely target for prolonged human presence. Still, the world could be transformed into a farm world, to feed the future floating colonies in the atmophere of Uranus (which would mine Helium-3 and Deutirium). Being the closest to the ice giant, ships traveling back and forth would spend minimal fuel. A skyhook could even be built connecting the upper atmosphere of Uranus with the moon.
Ariel[]
Over twice the size of Miranda, the fresh non-eroded surface of Ariel gleams with the highest albedo of the five moons. Having 2.64% the gravity of Earth and a diameter of 719 miles, Ariel would probably be a better candidate in terms of temporary human presence than Miranda. Its surface and mantle are rich with water, methane, and ammonia ices, which settlers could mine. Agriculture for supplying Uranus inhabitants with food could also be a possible purpose for the moon.
Umbriel[]
This moon is a twin in size with Ariel, but has an older, dirtier surface and is less dense. Humans could use it as a penal colony of some sort, or turn it into a farm world like Miranda or Ariel.
Titania[]
Titania is the largest moon of the Uranian System at 980 miles in diamter (larger than Rhea). Its surface gravity is a bit more than 1/27 of Earth's gravity (or 3.76%), which is possibly enough to counteract with drugs and excerise for a limited time. Titania's orbit is the second farthest from the planet, making it the least bombarded by charged particles from Uranus' radiation belt, while still inside the magnetic field. This is definitely a moon we should consider establishing at least a base on, to help humanity adapt to and colonize objects further and further from the sun. Titania also contains a rich abundance of ices and may even have a subsurface ocean, making it a prime terrraforming candidate.
Oberon[]
Oberon is similar in size to Titania, but has several differences. First its orbit lies completely out of Uranus' magnetosphere, leaving it vulnerable to cosmic radiation. The surface of Oberon is also much older and darker than Titania's. But like all the large Uranian moons, it is composed of nearly equal parts ice and rock (in fact denser than most of the moons of Saturn). This moon along with Titania could be potentially terraformed through the addition of artificial heat, concentrated light and greenhouse gases.