IE in terms of vocals, songwriting etc.
The long haired, moustache-less Freddie.
Or
80's Freddie.
Its a hard one.I like the smoothness of his vocals in early Freddie and he could hit the REALLY high notes. But 80's Freddie was more exciting and the live shows were much better.
As a composer: 1974/76 era.
As a live performer: 1979/82 era.
Recording lead vocals in a studio: there's so many high points, but some of his finest efforts were some of the last ones: Barcelona and Innuendo, for instance.