I wish I could directly comment, Brian, but believe it or not I have yet to see either of those. But I love Joan Hackett (especially her work in The Group, The Last of Shelia and Reflections of Murder), so as much as I've enjoyed Lysette Anthony in what I've seen of her work, I find it hard to believe I would prefer her performance to Joan's. But without having seen either, that's simply an impression.
One of these days I definitely need to check them out...