I have been to all three Alila hotels in the California. Definitely Alila big sur is the best (It might be one of the best hotels in California). Alila Marea Beach and Alila Napa are comparable IMO. Both are very nice and decent boutique hotels, and you would have a good time staying there. But it does not won't make you feel "WOW". The major highlight of Alila Marea is that you are ocean front and you would have an easy access to the beach. But other than that, nothing stands out that much. The pool is very small and crowded.
I have posted detailed hotel review for all these 3 Alila hotels in my YouTube channel. Feel free to check it out.