Life in the outer Solar System could be much stranger than life in the inner parts. Mars could be the closest to how Earth is now, with Venus being next closest. Only the planets and moons that can be relativly easily terraformed are on this list.

Mars is half the size of Earth. If Mars was terraformed Mars would be similar to Earth, but much smaller and we might have difficulties keeping the atmosphere from burning off, as Mars doesn't have a magnetosphere.

Venus is almost the same size of Earth. Venus has a atmosphere that is currently very toxic to humans. If Venus's surface temperature cools down enough by finding a way to remove a large portion of the greenhouse gases from the atmosphere, we can help change Venus' atmosphere by getting carbon dioxide and other harmful gases low enough to spread plants along the surface, which can absorb the carbon dioxide and turn it in to oxygen. However, we would need a way of keeping the plants alive which means finding a way to keep water near the plants long enough for Venus to be able to keep water on the planet without it boiling away. One way to do this is when the oxygen on Venus gets to an optimal level we can introduce more hydrogen into the atmosphere so that Venus could have its own water.

Moons of Jupiter

Europa is a moon of Jupiter. Europa could have a great variety of sea creatures if we can warm Europa up. It is still possible to have a ice pole where the sun will not reach.

Ganymede is a moon of Jupiter. Ganymede is also similar in size as Mars and it already has a Magnetosphere. It is also possible that Ganymede has liquid water under it's surface, and to warm Ganymede up we could also introduce some greenhouse gases into Ganymedes atmosphere

Moons of Saturn

Titan is a moon of Saturn. It is a really large moon compared with the other medium size moons. The plants that might start off Titans new atmosphere might absorb some of Titans past atmosphere before it gets fully terraformed. Titan has some unique advantages such as its abundance of nitrogen and water ice. Although Titan can sustain an atmosphere, it is extremly far away from the Sun. If giant mirrors were to be put around Titan, dramatic change would happen to the environment. There are rich amounts of ammonia below the crust. Lots of ammonia would have to be erupted by the cyrovolcanoes to warm the satellite even more.