5- 2003 because MNOG 2
4- 2008 The infamous awakening of Mata Nui was epic. Was arguably the grand climax of the Bionicle story.
3- 2001 They definitely started off with a bang. You would think that Lego would play it safe with the new line and take things slow....but they went on and created a full blown universe with its own unique thing right from the get go. The confidence that Lego had in Bionicle was what made it amazing.
2- 2006 Not only was it the year that I was introduced to Bionicle, the whole new gritty, stormy, and darker motif and ambiance was very unique and new to the whole tribal/technological feel of Bionicle. Villains were the best.
1- 2007 Bionicle was already mysterious as it was. Adding a deep sea environment with creepy sea monsters was a home run. Plus, Creeping in my Soul was the best song.