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There is no such thing as a native UI for Linux because Linux has nothing to do with UI. As a kernel, it really only functions as a part of what you could see as a complete operating system.
If you want to have a native UI then you have to focus on the platform used for the UI, not just some kernel. Popular desktops that are used in combination with the Linux kernel on a GNU system are KDE and Gnome. I use Trinity. These desktops can work with different types of underlying operating systems, which may be interesting to support as well.