In general? In the same vein as my preferences, it's all pretty much unpredictable. There are the lightning isles, the country of Wano, the Marine Bases, the hovering islands, mechanical islands...

'The New World' is a sea of madness that kills the weak and sends normal men home, broken.

[One could easily see why it was that Law enjoyed venturing through it so much. The move all the way to the end of the Grand Line was one he planned on going through in utter chaos.]

So, you could guess why it is that this boring quiet would get to me.