I've mentioned the names of a handful to some others, but quickly again: various types of dualism (substance and property), monist views like George Berkeley's idealism, and non-reductive physicalism.

I mention above that Sean Carroll is diving into philosophical questions here. If you'd like to learn more, then depending on your expertise, you could look up more on philosophy of mind -- there's a lot of literature. There are also scientific investigations that may be of relevance to these questions to, such as near death experiences, out of body experiences, that sort of thing. I don't think that those sorts of experiences actually would settle the discussion either way, but they are interesting and relevant nonetheless. I haven't watched the video that this HN article is about yet.

When you mention singular or plural, are you asking if I think there's just one mind or many in our universe? My own personal view, I think there are many minds in our universe (is that what you were asking?). I lean towards an idealist view similar to, but not the same as, George Berkeley's. One where mind/mental is the fundamental substance, and the physical world exists on top of that mental substrate. Mine is a pretty uncommon view though. Most people are physicalists of some sort or dualists, I think.