What is better method to use if I would like to provide the user with some information about my Hardware device.
Should I develop a proprietary COM Library or should I develop a WMI provider?
I think that's a no-brainer: WMI is the Microsoft-blessed way of providing performance and hardware information.
That should be the way you provide the information you describe. There's plenty of precedent in the Win32_Computer and other hardware classes, which provide CPU details, memory size and so on (stuff that doesn't change with the software running).
I say that since you specifically marked out "hardware device". Don't think that WMI is for reporting just software type things like memory usage or process lists.
There's a large amount of software out there already specifically built to query WMI (including one of mine) so there's no shortage of people who will know how to do it.