26 hour layover: Dublin or Belfast? (Or somewhere else?)

Hi! Second time visitor with a long layover in the Dublin airport next month and some trouble deciding where to spend it.

On my previous visit I stayed in Dublin but did day trips 4 out of 5 days I was there, one of which was to Belfast. I did a mix of touristy things and wandering around in Dublin, but generally enjoyed everywhere else I visited more. In Belfast I only had time for a Black Cab tour before exploring the northern coast.

I’m considering Belfast because I am deeply interested in the history and politics. I have every book that I can get my hands on and watch every documentary I can find. My biggest priority would be to see some historical sites. I would really only have time for a self guided tour, but honestly that’s fine with me. The biggest con is that I know a 3 hour train ride one way is a waste of time.

The obvious choice is to stay in Dublin. I know that much of the city would be new to me and I’m not exactly opposed to this option, it is just less exciting. If I did this, I would be mostly prioritizing hanging out at local places and looking for souvenirs and trinkets from places other than the major tourist shops.

Alternatively open to closer towns to explore! Have to be accessible by train, but that’s really it.