My preference is to base in Antwerp, especially if your NL train happens to go direct to Antwerp rather than to Brussels. Cologne is an easy direct two hours from Brussels, but much cheaper by advance purchase, barcode ticket printed at home. (Do you want to stop in Aachen?) Many local trains per hour from Antwerp to Brussels (3 stations, note where the Cologne train departs from.) Antwerp can't be seen in a day, and has lots of things to view and do.
It is totally unnecessary to change hotels in this part of Belgium. There are very frequent, unreserved commuter trains between Bruges and Ghent and Brussels and Antwerp. It is possible that some people at cocktail parties back home will say you should have slept in Bruges, but I consider that romantic notion to be incorrect. (OPINION.) Antwerp is a good location for daytrips in any direction. I have had to wait in ticket lines because my State Department Federal Credit Union Chip-and-PIN credit card wouldn't work in the Belgian ticket machines. Haven't been there in six years though.
Edit: Note that in all these cities, the historic center is not at the train station. It's typically a 15 minute walk or a short tram or bus ride. There is a bus ticket machine outside the train stations. Except for Brussels, the same agency runs the trams and busses in the other three cities, so you might buy a 10-trip for convenience.