Op.15/1 in F major
Op. 32/1 is actually one I like a lot. In my opinion, there are a lot of elements of surprise with the way the theme is developed and the melody evolves, culminating with the shocking coda. This provides such an interesting "journey" every time I listen to it.
The op 55 no.2 nocturne is really amazing and really underrated in my op.
(New to Piano Street!) I am actually a huge fan of Opus 37 no 1 in G minor. For whatever reason none of my friends agree with me. But I love how somber and bittersweet this nocturne is, it's great to sit down and play after a bad day. The chorale section in E flat is relaxing. The picardy ending will often give me chills, as it is a more emotionally powerful ending than a minor one.
op. 27 no. 1, as someone who doesn't care much for chopin the middle is a blow. It's so beautiful and fun to play.