1º The songs, of course. As ChiliD said, with few exceptions, they are all great.
2º
Rumours
3º Their first two female members... they gave the world two divas: Stevie Nicks and Christine McVie.
4º The soap opera of course!!! Beginning with Buckingham/Nicks, and having their last chapter at
The Dance... but it's not over yet!!!
5º The great musicianship that all of the line-ups have been able to have... I think there is no exception on this, even the
Time incarnation sounded very well.
Song of the moment - Brown Eyes