>>58170592001-2003 are considered "the golden years" and it really shows, especially in the departments of creativity and having a unique tribal atmosphere, among other really nice things (mostly courtesy of the mata nui online game). The figures really don't have any posability in these years, like, at all. Instead, the focus is put on function.
I wasn't really there to experience the golden years in full, but I do think they are the best years.
After the golden years, stuff gets really complicated plot and lore-wise. The figures continue to retain function, but completely lose any gear related functions in 2006 (so glad G2 brought them back).
I don't blame you for disliking 2008 and 2009; not many people really liked those years anyway.
G1 was always a lot more mature and developed than G2 has been (and probably will continue to be).
If you only really care about sets, might as well stick with G2, but if you have some extra cash then just get a bohrok. Everyone loves the bohrok.