Day trip from Amsterdam: Haarlem, Utrecht, or Den Haag?

It's June. None of the many Amsterdam area daytrips is to an undiscovered place. There is the most old stuff to see in Delft, but there is more art in Den Haag. There is modern architecture in Rotterdam. Utrecht or Leiden are good compromises, and both have multiple museums.

I never no how to answer these “what would you do” or “which would you choose “ questions, for the simple reason that I don’t understand why it would be relevant what I would do. I’m not you, and you’re not me.
All three cities you mention have architecture and history. And compared to Amsterdam, all are relatively uncrowded. It would help to know why you’ve narrowed it down to these 3 cities. Why haven’t you considered Leiden for instance?

…I don’t understand why it would be relevant what I would do. I’m not you, and you’re not me.

Yes, obviously. I’m not asking what I should do. I’m asking what you would do given the priorities stated. Don’t overthink the question.

And my question literally said “or some other place?” So Leiden fits that.

Like I said, all the three cities you mentioned have art and architecture. And so do Delft, Leiden, ‘s Hertogenbosch etc.
So what I personally would do if one of these cities doesn’t stand out to me, is let fate decide; write the names of the cities you’re considering on pieces of paper, throw them in a hat and pick one.

My choices in this order would be
Haarlem
Utrecht
Gouda (we love cheese)
Rotterdam
The Hague (we were there last May and the city was doing major construction, don’t know it is is done)
We haven’t been to Leiden

I would combine the charm of Delft and wonderful sights of Den Haag. The two cities are adjacent to one another and easily connected by way of train, tram, or bike. I would start with Den Haag to hit a couple museums, maybe hit the beach for a bit if the weather is nice then make your way to Delft and wander. Grab a meal in Delft and head to the station back to Amsterdam.

One option would be to take a fast train to Rotterdam and then work your way back up, with possible stops in Delft, Den Haag and Leiden. You could also go a bit further and start in Dordrecht. I think there will be crowds everywhere this time of year.

Utrecht or Leiden for a full day visit - boat trip, lots of life, restaurants, museums etc.

Delft for a quaint half-day wander. Easily linked by team to Den Haag for the Mauritshuis museum. And onwards (same team route) to Scheveningen for the beach on a nice day.

Dutch trains and trams are so easy between all these places. Just tap and pay.