Speculation: First habitable exo-world?

[PlutonianEmpire]

This thread is purely speculation. What kind of world do you think the first habitable exo-world discovered might be?

For this thread, assume habitable means reasonably Earth-like, and in the habitable zone of its sun(s), with all the things that come with it.

Admittedly, some of the options may seem redundant, but as always, the universe is full of surprises.

For "additional sun(s) elsewhere", just think of systems like Alpha Centauri or Polaris, but with planets.