For me, I always loved the Piraka, they were fleshed out so well in the first 5 Bionicle Legends books. HOWEVER, my favorite for each period are as follows:
2001-2003: Kopaka 2004-2005: Nokama and Nidhiki 2006-2008: All the Piraka + Takanuva 2009-2010: Mata Nui
These are mine:
2001-2003: Kopaka and Takua/Takanuva 2004-2005: Nuju and Vakama 2006-2008: Matoro, Dekar/Hydraxon, and pretty much all the villains 2009-2010: All the Ice Glatorian/Agori
...Yeah, I'm always partial to the ice guys.
The ice characters tend to be the most rational, level-headed, and intelligent characters. Characters like Kopaka especially get their share of just straight-up cool moments. So I can't blame ya there.
2001-2003: Kopaka and Takua/Takanuva 2004-2005: Nuju and Vakama 2006-2008: Matoro, Dekar/Hydraxon, and pretty much all the villains 2009-2010: All the Ice Glatorian/Agori
...Yeah, I'm always partial to the ice guys.
The ice characters tend to be the most rational, level-headed, and intelligent characters. Characters like Kopaka especially get their share of just straight-up cool moments. So I can't blame ya there.