Well, if the emphasis is on "best" then my first thought is
Brideshead Revisited by Evelyn Waugh - one of the great novels of the 20th century. It tells the story of its narrator, Charles Ryder, and his association with an English Catholic aristocratic family. He first falls in love with the Sebastian in college, and then later in life with Sebastian's sister, Julia in between the two world wars.
There was also a spectacular TV version (11 hours) done in 1981 starring Jeremy Irons that follows the book almost to the word. If you are interested, see that rather than the 2 hour 2008 film that hacks the meaning out of the story and turns it in to a family melodrama.
But, the book is the best. There is also the Audible Audio book which is read by Jeremy Irons which is kind of the best of both worlds.