QUESTION: One Piece. (Patreon)

What are the MUST WATCH arcs of One Piece?

As most are aware we are currently going through the manga of the smaller and arcs not deemed essential to react to the episodes of as it's much quicker catching up and safer for copyright but which ones ARE really needed to be watched?

We're currently reading Drum Island which I've been told is best but is the upcoming Alabasta arc worth watching?

Sky Island etc?

Any help is welcome!