I think microkernel's are weird but everything I hear does seem to imply they are better then what we currently have. That being said, "microkernel's are the future" is a pretty old take now and I don't know any OS that has one.
Linux is monolithic. Windows is somehow monolithic, bloated and extremely minimal. Don't know about apple but I would guess they're also monolithic since they are old and Unix based and that combination generally means monolithic.