Set sail to the most habitable world outside of Earth! Whatever we deem the most likely exoplanet to be earthlike on the day our fusion drive starts the acceleration burn, that's where I'd want to go looking if there's a second evolutionary tree to explore.

How did they solve heat management? Did they develop photon-sensing organs like we did? What's the mechanism for passing genetic information between iterations (maybe they don't call them generations)? Do they flap their meat to communicate, the way earth animals' vocal tracts do? Are they made out of meat?

And if there is no life, I'd learn a lot about geology, the local solar system and, subsequently back home, all the more appreciate what we've got going on Planet A ❤️