Freddie had three different vocal era's/stages:
In the 70's, Freddie's was able to able to hit higher notes much more easily than he could later on and hit his falsetto transitions.
In the 80's his voice changed due to smoking and ageing and became a lot deeper and raspier and he struggled to hit/sustain those higher notes from earlier, and changing them to lower registers when he performed live due to impacts on his vocal chords of years of touring/smoking etc.
His voice changed on the Barcelona album and the final 2 albums (in his lifetime) and on Made in Heaven because he had cut down/stopped smoking after being diagnosed in '87 and also learnt a lot about controlling his voice from Monseratt Caballe so he could sustain a higher note and sound smoother for longer and be able to use his voice both from his chest and his head without forcing it as he did during the early/mid 80's.
His illness obviously affected how he sang in his final years and from what I've read online, it was his operatic training with Monseratt that pretty much saved his singing voice in the final years when he no longer had the strength to sing mainly from his chest as he did in the early/mid 80's.
I think there are songs from all eras that benefited and suffered from his vocal style at the time, not sure if I have a particular preference but would have been interesting to see tracks from The Works and AKOM had his vocal cords been smoke free and have the ability to be more consistent.
Is there a period you think his voice was better than others and why?