The great debate: At 50, is 'Sgt. Pepper' The Beatles' best album?

Sgt. Pepper's Lonely Hearts Club Band, lauded for its sonic sophistication, sweeping diversity and experimentalism, stands out in The Beatles' catalog as their most historic and celebrated album.

But 50 years on, is it their finest? After being ranked first among Beatles discs and at or near the top of best-album lists for decades, it has been losing ground to Revolver, long gunning for that position.

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Sgt. Pepper, released June 1, 1967, in the U.K., placed first in a 2003 Rolling Stone poll to determine the 500 greatest albums of all time. Revolver was No. 3, Rubber Soul No. 5 and The Beatles (more familiarly known to fans as The White Album) No. 10. In a 2012 Rolling Stone reader poll ranking Beatles albums, Revolver prevailed by two votes over Abbey Road. The Beatles ranked third, with Sgt. Pepper fourth.

In the 1994 book All Time Top 1000 Albums, Sgt. Pepper was No. 1 and Revolver was No. 5. By the 2000 edition, Revolver held the top spot.

And on the fan site BestEverAlbums.com, Sgt. Pepper is ranked as the third-best Beatles album and fifth among all albums. Sgt. Pepper leads the Rock and Roll Hall of Fame's Definitive 200 albums list. Revolver crowns Q magazine's list of 100 greatest British albums ever.

So is Sgt. Pepper the Fab Four's finest? USA TODAY asked three Beatles scholars and experts to weigh in, but the debate is by no means settled.

'RUBBER SOUL'

Martin Lewis, Beatles scholar who worked on The Beatles Anthology:

"Revolver has a metallic, hard edge to it," says Lewis, who prefers 1965's Rubber Soul. "Rubber Soul has a heart and softness that's very evocative.

"Sonically, Sgt. Pepper is their best. There is a crispness and richness and Technicolor glow that comes off that album. It's a rich feast. But the songs are not as deeply felt and personal as songs on Rubber Soul.

"Rubber Soul is this great transition to a more sophisticated Beatles. There's warmth, emotion and a level of maturity beyond their years in songs like In My Life. Rubber Soul is their last quintessential English album. It's very Edwardian."

'REVOLVER'

Bill King, editor of Beatlefan magazine:

1966's Revolver "represents the group at its musical peak," King says. He calls it "a stylistically diverse collection of top-notch songs with sophisticated, thoughtful lyrics imaginatively arranged, recorded and performed."

The album "marked the band's transition from teen idols to musical legends," he says. It saw John Lennon master psychedelia with She Said, She Said and Tomorrow Never Knows, but it was Paul McCartney who "moved to the fore as the group's dominant songwriter" with such classics as Eleanor Rigby and Here, There and Everywhere.

And "while Pepper gets the credit, it was Revolver that sent a message to The Beatles' contemporaries that it wasn't necessary to stick to a hitmaking formula. You could take chances and still sell records."

'SGT. PEPPER'

Matt Hurwitz, Beatles historian and Mix magazine contributing editor:

Hurwitz endorses 1967's Sgt. Pepper for its sublime studio ingenuity and music that is "simply magical."

"They were always pushing the boundaries of current pop-music recording craft," he says. "Every new release was awaited with excitement: What would The Beatles sound like this time?

"Sgt. Pepper was perhaps the most highly anticipated release by any group in the 1960s. They had stopped touring and were now solely focused on recording craft. The idea of a rock album with a theme — something taken for granted today — was a cultural shock. They changed the way pop-music recordings were made forever, mainly by asking, 'What if we ... ?' The result was a masterpiece and an experience one never tires of."

'ABBEY ROAD'

David Bedford, founder of the new Beatles Social Network:

The Beatles peaked with 1969's Abbey Road, Bedford says.

"The band that was falling apart went into the studio for the last time and created an incredible album that displays the songwriting skills of John, Paul and George (Harrison) on equal terms," Bedford says. "Harrison contributed some of the best Beatles songs ever recorded, with Something and Here Comes the Sun. They seemed to be in perfect harmony, yet this was the last time they would come together to make a record.

"It always makes me think: Maybe, just maybe, they could have continued releasing albums together, even if they were recording mainly on their own. But it was their last, and what a way to sign off.

"Pepper was the most revolutionary album they made. It was a game changer in so many ways that most great artists would like to measure themselves against. My favorite (most of the time) is still Abbey Road, but Sgt. Pepper will always be their most important album."

Contributing: Kim Willis