Thats a diffficult question to answer but since you asked my favorite cd of Freddie's is "Freddie Mercury Solo"
containing  Barcelona and  Mr Bad Guy.   Followed by Made in Heaven,  News of the World and don't you dare relieve me of any cuz I  truly love 'em all.   Now his Interviews are priceless right up there with his music.  I have one that I listen to at least once a month.