Keith Ward gives a concise overview and defense of metaphysical idealism:

This lecture is essentially a summary of the argument from his 2010 book More Than Matter. The basic claim is that mind or consciousness is a fundamental component or aspect of reality, and it can’t be reduced to or explained exhaustively in material terms. Ward points out that we’re immediately aware of consciousness, while the material world–at least as it appears to us–is something that is in part constructed by our minds. This doesn’t mean that the physical world isn’t real; but it does suggest that there’s something problematic about arguing for the reduction of mind to an aspect of reality that is itself partly mind-constituted. Minds are the only “things-in-themselves” we know first hand. On that basis, Ward says

What idealists maintain is that the ultimate nature of reality itself is mind-like, and that human and other finite minds are the best clues we have to what objective reality is like. The cosmos is not a mindless, unconscious, valueless, purposeless, yet somehow strangely intelligible, mechanism. Such a view is the result of extrapolating a machine-model, very useful in many scientific contexts, to provide the most comprehensive and adequate picture of the real cosmos.

Idealists propose that the human mind provides a better model from which to extrapolate to the cosmos as a whole. That is not because the cosmos looks like a very large human person or because there is some large person hovering just beyond the cosmos. It is because human minds play a creative and constructive role in producing the phenomenal world. They seem to point to a level of reality that is not merely phenomenal or an appearance to consciousness. Human minds generate an idea of reality as mind-like in a way that far transcends human mentality, yet that does include something like consciousness, value, and purpose as essential parts of its nature. (More Than Matter, p. 58)

Ward doesn’t claim to offer a knock-down argument for idealism, but he thinks it’s at least as reasonable as competing views, if not more so. He also points out that some form of idealism is arguably the majority view in the history of philosophy.

Even when I was an atheist, I never found materialism particularly compelling. And studying philosophy–particularly early modern philosophy–only reinforced that. It’s hard to come to grips with the arguments of Descartes, Leibniz, Locke, Berkeley, Hume, and Kant and still think that materialism is a straightforward, much less obviously true, understanding of reality.