In terms of stations I’ve had the pleasure of visiting, these are a handful of notable ones not mentioned yet:
Liége-Guillements:
The scale of that arch above makes the station feel significantly more grand than the just 9 platforms it serves. That being said, it’s notably not that comfortable, there’s not much in the way of shops, it can get cold, and rain can get through with some wind.
Arnhem centraal:
The platforms themselves are quite futuristic, but the station concourse and exterior with its flowing lines are what’s really impressive. There’s not much in the way of station amenities though.
Antwerpen-Centraal:
There’s something really special about taking the escalator up and seeing an intermediate level of trains. The beautiful old concourse up front is of course also a highlight.
Rotterdam Blaak:
Someone else mentioned Centraal already, which is also nice, but I found this 70s styled mostly underground station oddly charming with its colourful platforms, murals, and lighting. It also has a small archeological display of some historical items they found during construction. It might not be the most interesting train station, but in terms of underground train stations (excluding metro stations that is), it’s probably one of the more nicer ones.
Amsterdam Centraal:
A beautiful but not be a particularly unique looking station. But I’ll let you in on a lesser known secret that is bound to improve your experience. For the price of a (mediocre) coffee, can you get access to one of the most best looking and charming (defacto) station waiting rooms in the Netherlands. Go to platform 2 on the East side, that is on the actual platform, not the concourse, and keep walking east until you see a sign for aforementioned mediocre coffee. You might hesitate at the sign, but enter it anyway. Trust me, you’re not here for the quality of the coffee. You will need to exit the OV-chipkaart gate however.