But pundits, pleez note: Whiz wasn't first historically, and it's no runaway favorite regionwide.
At John's Roast Pork, which serves up taste-test winners on Snyder Avenue, the processed cheese sauce isn't even served.
"I'm a cheese eater, sweetheart, and I love cheese, but Whiz is not cheese," says owner Vonda Bucci, 75. "It's a lot of grease and coloring."
"We won't do it. We will not carry Cheez Whiz," said Jack Mullan, 50, co-owner of popular Leo's Steak Shop in Folcroft. And customers never complain.
A recent Philly.com poll asked, "What cheese belongs on a cheesesteak?" and Whiz finished third. American edged out provolone after more than 5,700 votes were cast.
Even Geno's owner Joey Vento, 68, downplays Whiz. "To be honest with you, I've never eaten Cheez Whiz, and I'm the owner," he said. " . . . We always recommend the provolone. . . . That's the real cheese."
The yellow runny goo, though, is the top choice of his customers - the locals as well as tourists, he said.
Ditto at Pat's King of Steaks, where Whiz oozed its way into history, said owner Frank Olivieri Jr., 44.
Originally, the Philly steak sandwich, invented by his Uncle Pat in the early 1930s, he said, had no cheese.
By and by, cheese was introduced. "Customers got tired of eating with or without onions, just like my Uncle Pat got tired of eating hot dogs," Frank Jr. said.
American or sharp provolone? was the original debate, he said.
In the mid 1950s - not long after Cheez Whiz hit the market - his father, Frank Sr., began keeping some by the grill, and telling customers to try it.
"It worked well, it tasted good. . . . It caught on," Frank Jr. said.
Other places started "impostoring us," he said.
But not immediately.
Patent attorney Stuart Beck, 67, remembers American as the standard for steaks in the mid '50s and early '60s when he was a student at Overbrook High, and later at Drexel University.
He ate at places like Larry's on Lancaster Avenue, home of the legendary "belly filler," and recalls being served American at Jim's in West Philly in 1955.
"I knew what Whiz was, because I worked in a supermarket, but it was never offered when you went into one of these places," said Beck, who lives in Wynnewood.
Back then, people even asked for mozzarella, he said.
As Whiz became popular at Pat's, American and provolone went out of favor, and weren't reintroduced there until the mid-1970s, Olivieri Jr. said.
Today, Whiz is "overwhelmingly the favorite" at Pat's, outselling runner-up American by 8 or 10 to 1, he said.
Pat's even has a Whiz warehouse that has 2,500 cases or more, each case containing six big No. 10 cans, according to general manager Tom Francano.
Where Whiz reigns, it pours.
"You might go through eight, 10 cases a day if you're busy," said Vento of Geno's.
"Whiz is a killer. I think Whiz is the best," said Marc Proetto, 42, owner/manager of Jim's in West Philadelphia. Customers prefer Whiz 2-1 over American, he said.
Calling Whiz a killer conjures up clogged-artery jokes. But, in fairness, Whiz - mostly whey, vegetable oil and milk products - is lower in saturated fat than American or provolone. Provolone is second-lowest, but lowest in sodium.
"So American loses," said Althea Zanecosky, registered dietician. "The other two, it's a matter of personal preference."
American takes the biggest slice at many other places - even another heralded South Philly spot, Tony Luke's on East Oregon Avenue.
Owner Tony Luke Jr. confesses, though, he loves Whiz.
"To me, it's always been Cheez Whiz," said Luke. " . . . I always say Whiz. I never say American."
Unless you're talking chicken cheesesteaks - what Hillary Clinton ordered at Bocella's in Conshohocken on primary election day.
"With chicken steak, it's always American," Luke said. "I won't eat a chicken steak with Whiz."
At Big John's in Cherry Hill, American is consumed six times as often as Whiz, and provolone is No. 2, said general manager Rebecca Ryan, 31.
Provolone is far and away No. 1 at the White House Sub Shop in Atlantic City, which doesn't even offer Whiz.
It's a split decision at Steve's Prince of Steaks. "Honestly, it's about 50-50," said owner Steve Iliesecu, who has two locations in the Northeast, one in Langhorne, another coming in Cherry Hill.
Some customers even order "combo" cheese - a mix of Whiz and the pourable American he invented in 1980, he said.
"The whole Whiz thing is overrated," said WIP midday cohost Glen Macnow, who had provolone during his "ultimate cheesesteak" search, won by John's Roast Pork.
"The advantage to Whiz is that, because it's runny, it spreads throughout the sandwich," he said. "But a good grill man should know how to melt and distribute American or provolone so that it infuses every crevice."
Contact staff writer Peter Mucha at 215-854-4342 or email@example.com.