I think the best target for off-world colonization is variously designed giant space stations in orbit around Earth and, later, sharing Earth's orbit (maybe lagrange points) around the Sun.

To create the best possible life for humans offworld, we'll need VERY close contact with Earth for a long time. I mean Amazon Prime delivery close. Coming down for family Thanksgiving close. Lots of sharing and experimenting as easily and cheaply as possible. We don't want to have to adapt to the random features of some other natural body that's far away and not very good. We should learn how to build an artificial body that has exactly the features we love and then, when we've learned how to make a great place for humans to live in space, replicate them, which will be easier if the whole thing was man-made to begin with.