The answer is somewhere between cutting-edge technology and good old-fashioned team spirit, according to the sailors, designers and engineers who are hoping to win the 165th edition of yachting's most prestigious event.
"I think the most important thing is actually going to be team culture -- the team that can hang together and make good decisions together," Nick Holroyd, the design guru for Softbank Team Japan, told CNN's MainSail show.
America's Cup veteran Dean Barker, who is heading up the first Japanese-flagged challenge since 2000, feels ultimate success will "come down to having the best equipment."
In December, the competing nations will launch their final AC50 race boats for next year's competitions in Bermuda.
Each has worked in near-total secrecy as they develop what they hope will be the technological innovations that make the key difference out on the water.
The wingsail catamarans will be 50-foot long, weighing 2.4 tons and crewed by six sailors. Their top speeds will be in excess of 45 knots (50 mph), using foiling technology that raises the boats out of the water to reduce drag.
The approach will differ from team to team. Britain's Land Rover BAR, for example, is using artificial intelligence
-- computer wizardry performing tasks that would normally need human intelligence -- to analyze every aspect of boat performance.
Led by multiple Olympic champion Ben Ainslie, BAR heads the 2015-16 America's Cup Match Racing Series standings
following last weekend's penultimate leg in Toulon.
But will machine or mind turn out to be the factor that wins the day in June?
Technological innovation is not all there is to it, says Jimmy Spithill, skipper of defending champion Oracle Team USA, who thinks lifting the trophy "will come down to the people and, ultimately, the better team."
Spithill and his crew have been undergoing a punishing training regime which pushes them to their physical limits, helping them to make split-second decisions in exhausting race situations.
Ainslie, seeking to win the cup for Britain for the first time, says each boat's daggerboard -- a blade-like element that reduces leeway, the sideways effect of the wind on the boat's course
-- will prove "the biggest differentiator in the performances."
"When you look at Bermuda, it is a very difficult venue to design for because the conditions are so variable," he tells MainSail.
Even in a three or four-hour racing window throughout the day, the conditions could change markedly.
"You won't be able to change that daggerboard once you're out there on the water and racing, so it's being able to be competitive in a range of conditions -- you might find at the beginning of one day a certain team is performing well and as the conditions change another might be more dominant," Ainslie adds.
"It will be the toughest challenge for all of the teams and all the design teams, getting the daggerboard design right."
Engineer Mauricio Munoz, one of the brains behind Land Rover BAR's use of artificial intelligence, feels those responsible for masterminding every last detail of the final boat will turn out to be the kingmakers.
"From the technical perspective I think it's definitely the design efforts, making sure the sailors are well acquainted with the pros and cons of the technology that they fit to the boat," Munoz says.
"So basically an understanding of what the performance profile is of the boat... and feeding this technical information back to the sailors and understanding what it is that actually makes the boat go faster from a design perspective, and having the sailors really have trust in that particular result.
"That's what's going to bring the cup home."
And in less than a year from now, we'll know who was right -- and why.