Well, I like Pelgrom too, but the light level (medieval cellar, not "romance") is too low for reading, which is what I do when I'm a solo diner. I'm afraid I've never looked for a steak in Antwerp. There are some Argentinian restaurants, but I suspect some of them might be franchises. The best steak in the area (French beef) I can imagine would be Het Meulderke in Turnhout, but it's not really accessible by public transportation. Lower budget, and other red meats but in Antwerp might be Persepolis, a modest Persian restaurant near the Jesuit church and the public library.
One of the restaurants on Grote Markt used to have "stone steak", with a fiery-hot stone delivered in front of you to cook your pieces of steak. But they gave it up. Maybe someone else in Antwerp does it now.