The weather in the west was better than in the east. So I was looking for a trail in the west, and I ended up hiking the jura crest trail from Vue des Alpes to Noiraigue.
I took the train to La Chaux-de-Fonds and from there was a bus taking me up Col de la Vue des Alpes. And then about 23 km, 900 m up and 1500 m down till to Noiraige. From there goes a train to Neuchâtel.