I like to know straight away who's talking so I voted for chapter headings. Unless it's important for the story that I be kept in the dark e.g. the murderer is talking but we don't know who that is yet. Putting the information in the first paragraph would seem like a delicate balancing act to me. Make it too obvious and it seems clunky, not obvious enough and it's frustrating as I'm distracted by trying to work it out. Either way it would take me out of the story until I was happy I knew who it was.
Having the name in the chapter heading if it's not needed seems like no downside to me.