Murray or the Fed? It's not a question about sport, but about the kind of person you happen to be. What matters more to you? Patriotism, if you are British, or excellence? Is sport about partisanship, or is it about the pursuit of perfection?
Andy Murray will walk out onto Centre Court on Friday knowing he faces a crowd utterly divided on this issue. He would normally be assured of a one-sided backing, but Roger Federer has a following that has nothing to do with national boundaries or parochial loyalties.
Federer inspires loyalty from everyone who likes to cheer for the nation of excellence. That's partly because Federer offers a very particular kind of excellence. It's not just that he's a very good player. It's not even that he's the finest tennis player of all time.
Federer's excellence gives a special kind of delight to those who watch him in action. Centre Court is perhaps the most vivid arena in all of sports, and it has a response that it reserves for Federer alone. It's kind of a delighted, knowing chuckle.
The showcourt's reaction is the sort of privileged laughter that greets a moment of artistic revelation: when you see the point of a Magritte painting or realize where a labyrinthine sentence from Proust has taken you; when you grasp the point of a Japanese haiku, or a piece of music takes you to a place that is at the same time surprising and inevitable.
"Sometimes Federer makes it look as if his opponent is willingly contributing to the spectacle of his own downfall." Simon Barnes
It's the laughter that recognizes a stroke of genius, the moment when that genius reaches out and connects with its audience. It's like a moment of enlightenment experienced by a student of Zen: In a flash, you seem to understand everything; all has been explained in an instant.
There is a strange and delightful illusion that comes when you're watching Federer at his best. It's as if he's trying to create beauty for its own sake, as if artistic expression is the meaning and the goal of everything he does. We know that's nonsense, but that doesn't make the illusion any less compelling.
Federer is trying to win, of course. He's not really trying to summon up aesthetic bliss in you and me. That's just the extraordinary byproduct of the way he plays tennis.
There's also the illusion of complicity. Sometimes, Federer makes it look as if he and his opponent are taking part in a dance, a performance thoroughly choreographed and exhaustively rehearsed.
He conjures a picture in which it looks as if the opponent is willingly contributing to the spectacle of his own downfall, cooperating with Federer to create beautiful points; that he is willingly acting as a foil to set off the genius of the Fed.
I remember that first year Federer won Wimbledon in 2003. All the talk around the All England Club had been about racket technology and how it was destroying the artistry of tennis. It wasn't a great year to start that campaign.
The non-tennis talk was about the recent publication of the fifth book in the Harry Potter series: "Harry Potter And the Order Of The Phoenix." I remember writing a piece about the technology of Federer's racket: claiming that he had acquired it from Ollivander's wand shop in Diagon Alley and this Wimbledon should be called Roger Federer and the Racket of Fire.
I have never seen another tennis player who used serenity as a weapon. That was what Federer did during his period of complete dominance, when he was No.1 for 237 consecutive weeks. He used that status with complete ruthlessness: All players seemed to accept his dominance and to defer to the master. The best now, the best ever.
Perhaps the only thing lacking for Federer in his conquest of Centre Court hearts was a touch of vulnerability. That was imposed by the rampaging figure of Rafael Nadal. Nadal has asked uncomfortable questions about the extent of Federer's greatness; their head-to-head record is 23-10 in Nadal's favor.
William Skideskly, in his curious June 2015 book "Federer and Me," attempted to demonstrate that Federer's style of tennis had an inherent righteousness about it, arguing that this was a quality that Nadal's game utterly lacked. The interesting point is not whether that is true, but that for many people it seems to be true.
Skidelsky said that Federer's style, which stresses innate ability over simple effort, seems to be ethically superior to Nadal's. And if that's a little bit mad, it's still instructive, because it's the sort of thing that Federer can do to the people who watch him.
I've watched all seven of Federer's victories at Wimbledon, and when he beat Murray in 2012, prompting Murray's famous gush of tears, I felt torn in half.
I had been deprived -- if only for 12 months, as it turned out -- of the story of the first British male to win Wimbledon in "about 150,000 years," as Federer himself once remarked. But I had watched the Fed win yet again, and that was in the way an even better story.
It wasn't like catching up with the next episode in a soap opera; it was more like watching history being made. It was also more like watching a legend being constructed before your eyes, and that was, in a way, more satisfying than journalism.
That year, I remember getting a picture run of Federer during a change of ends. A man sitting on a chair may not seem like a great image, but behind him, someone in the crowd was holding up a hand-painted sign: "Silence! Genius at work."
If Federer has one more slam left in him, it's surely Wimbledon -- on the grass, when points are shorter, there's less running to do and more opportunity for genius to trump effort. Every Wimbledon appearance Federer makes has the feeling of the last chance.
One more taste of perfection? All patriots for the nation of excellence will be cheering for that.