My staple film is Tri-X 400. It used to be TMax 400, but the shiny emulsion doesn't scan well in my Epson V700 scanner. I shoot everything and anything important with Tri-X, but once in a while I get a hankering for a slower and finer grained film, just to get a smooth print that looks like it was from large format.
Usually it's Fuji Acros that gets the nod, because of its absolutely irresistible highlight tonality. Then as soon as I buy a couple of rolls, and realize that it's way too slow for how I shoot, and I regret the impulse. But then a couple of months down the road, there I am again, looking at the Acros, TMX, and Delta 100... When will I ever learn?