Having used many rain jackets over the years while touring, I keep coming back to my Shower's Pass Elite 2.0, despite its weight and bulk penalties. In dry climates with the occasional storm, an ultralight jacket is fine. I bring a $30 5oz. O2 Rainwear jacket. In more humid climates with frequent rain, I believe that it's the jacket's ventilation features that are more important than its fabric. Even the fanciest waterproof/breathable fabric can't force water vapor from inside to outside if outside is just as humid as inside. These are the features that I think are crucial to a great ventilation design:

- generous fit to allow layering and airflow underneath but not so baggy that the jacket flaps on descents
- wide cuffs to allow airflow up the arms
- pit or side zips to allow airflow around the torso
- some kind of flap in the back to allow air that enters from the cuffs and pit zips to escape, otherwise the jacket billows and air isn't flowing effectively inside the jacket

Most of the jackets mentioned in this thread don't have all of these features. I would use them in dry climates but not when expecting more frequent rain exposure.