Henry hasn't exactly proven to be a good pass catcher. And imo, his hands are better than Dillon's. The Titans also don't run our system. Our system highly prioritizes a HB's ability to catch the football (and block) because of the way McVay schemes and how his offense works. It's why McVay grabbed Henderson. Yes, he was a fast, explosive HB who fit the outsize-zone running game well, but he was also a legitimate weapon in the passing game.
I know people think we need a hammer. I don't necessarily agree on that. But if we want a hammer, Zack Moss is a hammer who is a heck of a passing-game weapon. I think A.J. Dillon could be very effective in the right system, but like Jordan Howard, he's going to be wasted in the wrong one. You'll note that Jordan Howard was great in Chicago under John Fox and not that effective under Nagy (who then traded him to Philly). FWIW, these are the guys I like in the 3rd through 5th rounds: