From worst to best...with descriptions!
2010--Though Journey's End was great and the final ending was nice, '10 was, well...you know. If the Stars had been better, I might have a little more affection for it.
2005--'05, IMO, wasn't really necessary. The idea of Vakama betraying the team could have been done better, but Roodaka was a great villain.
2009--'09 was better than '05, IMO, because it had a fresher feeling. Still, the soft reboot idea didn't go as well as it could've.
2008--Though it was my first year as a BIONICLE fan, '08 had some pretty bland sets, though the story was intense and surprising.
2002--TBH, though having a unique story, the Bohrok were all clones, and there wasn't much that stood out about '02.
2004--'04 was good, but the abrupt transition from tribal to metropolitan was a little jarring, and the flashback concept was a little confusing. But, the Metru's development was well done.
2007--While it might not have been the year with the greatest sets, '07 gave us a group of tragic villains in the Barraki, and also gave us the most powerful moment in BIONICLE history, Matoro's heart-wrenching sacrifice.
2003--BIONICLE's first movie. This year revolutionized the story, bringing us the Nuva, Takanuva, and a long-awaited Makuta set. Takua's journey in MOL is what really makes 2003 great.
2001--The one that started it all. The mystery and intrigue of the environment really drew you in. The characters might not have been the most unique, but without it, BIONICLE wouldn't be here.
2015--I know it might seem a little controversial to put it so high, but 2015 is really close to what I think BIONICLE should be. The Toa sets were, IMO, the best team of heroes we have received so far, the villains were unique and mostly cool-looking. The only thing that keeps it out of the number 1 slot are the times where the story got a little too simple, leaving me wanting more.
2006--Most intense, most dynamic. The villains were delightfully evil and the heroes were both conflicted and determined to succeed. Greg's writing really excelled in this year, and he released what is undoubtedly the best series of BIONICLE books.