My favorite are Matorans of Mata Nui (2003). I just like that they combine some elements of Tohunga, some element of Toa and their own elements - just a nice mix. These guys were more articulated than Toa, and that was cool, not for Toa, but still. I just don't really like loose torsos because of functions (but it is easy to fix with blue pins) and lack of colored eyes. It was also strange to not include any Le- and Onu-Matorans. It's a shame that we miss Nuparu, Kongu and Onepu here, and can't even moc them properly without recoloring pieces with paints.
I also like Metru Nui Matorans. They are really solid and iconic looking to me at some point. They have some nice colors and proportions and don't look that invalid and clumsy as some other versions. But I don't like neck articulation, it's weird, nice for MNOG talking imitation only which is not for Metru Nui.