Big Ears
Music Lover
These are the studio albums and you can see a decline from Big Generator, with the exception of Keys to Ascension (in my opinion of course):
Yes
Time and a Word
The Yes Album
Fragile
Close to the Edge
Tales from Topographic Oceans
Relayer
Going for the One
Tormato
Drama
90125
Big Generator
Union
Talk
Keys to Ascension
Keys to Ascension 2
Open Your Eyes
The Ladder
Magnification
Fly from Here
Yes
Time and a Word
The Yes Album
Fragile
Close to the Edge
Tales from Topographic Oceans
Relayer
Going for the One
Tormato
Drama
90125
Big Generator
Union
Talk
Keys to Ascension
Keys to Ascension 2
Open Your Eyes
The Ladder
Magnification
Fly from Here