Cheers fans though are a divided bunch. Some prefer the Coach years, others prefer the Woody years. The Diane or Rebecca dispute is far more controversial.
For me I enjoyed the Diane years more. The chemistry between Shelly Long and Ted Danson was great and their characters on/off relationship gave viewers something extra to invest in whilst watching the antics of the other patrons.
Upon watching the later seasons the standard is far lower though, with weaker plots and the characters far too exaggerated from their original form. It happens with a lot of long running sitcoms I know, but when a Cheers episode was poor, it really was poor.
I forgive and forget the latter years though and celebrate the first five because that for me was when Cheers was well worth drinking to