The seven leading candidates for Oakland mayor (at least as defined by the Oakland Chamber of Commerce) had quite a lively exchange of ideas Tuesday night. As has become the custom for elections under the controversial ranked-choice-voting system, the candidates inserted a touch of strategic humility at every opportunity. The most common line of the night was, in effect, “I want to be your first choice for mayor … but if you really don’t think I’m the best choice, please pick me second or third on your ballot.”

Anyone who has been following Oakland politics over the past four years might think incumbent Jean Quan is highly vulnerable to a challenge. But she is making a game that Oakland is a “city on the rise” — as measured by restaurant openings, drop in violent crime, lower commercial vacancy rates downtown and in other areas — and that she is at least partially responsible. “I’ll put my record up against the last few mayors,” she declared. Don’t count her out, especially with the ranked-choice system, which has proved to be something of an Incumbent Protection Act in San Francisco. It puts a premium on name recognition for those second- and third-choice votes.

Here are some other highlights of the debate:

BEST LINE (from the right): “If you want to know what the real Occupy Oakland is, it’s the public sector.” — Joe Tuman. He was referring to the volume of county, state and federal office buildings that don’t contribute to the city’s tax base.

BEST LINE (from the left): “No welfare for billionaires.” — Dan Siegel, on his opposition to subsidies for professional sports. Not to be outflanked, Tuman said the Raiders need to “eat the ($120 million) debt” from the 1995 deal that lured them back from Los Angeles.

BEST COMEBACK: Libby Schaaf, dissecting Siegel’s contention that the Port of Oakland could be contributing tens of millions more to the city each year. Schaaf walked through the myriad legal reasons why “the myth” of a port windfall was illusory.

SPORTS CORNER: No question, the most enthusiastic advocate for keeping Oakland’s pro sports teams was Rebecca Kaplan, who not only expressed her determination to keep the A’s and Raiders, but … “we’re not done with the Warriors.” She pointed to the difficulty in getting a development to the finish line in San Francisco, where the team hopes to relocate. Bryan Parker also talked about how he “bled black and silver” and wanted to find a “responsible” way to keep the teams. Siegel and Tuman were on the more skeptical end of the spectrum. As for Quan, she talked about her “Coliseum City” vision and its potential for keeping both the A’s and the Raiders, but acknowledged that it still might not happen. After the event, she told me that her plan for a privately financed sports-retail-housing development at the Coliseum site would include a new hotel and a “covered stadium” that could be used for events other than football.

THE “LET’S GO OAKLAND,” HIGH-ENERGY CANDIDATE: Kaplan. The throng in the right-field bleachers of the A’s games would be proud of her Oaktown pride.

MOST WONKISH: Courtney Ruby, auditor, who at times sounded as if she were delivering a lecture at Harvard’s John F. Kennedy School of Government.

POIGNANT MOMENTS: Bryan Parker, talking about how the murder of his sister when he was 29 years old made crime a personal issue for him. Ruby talked about how a classmate of her 6-year-old son was shot in the neck. No volume of Quan’s statistics about a safer city can truly counter the reality that, for too many people in Oakland, crime is very real and very personal — and an issue in this race.

AND THE WINNER IS … Jean Quan, on the premise that a seven-way tie goes to the incumbent. The debate was lively, and each of her main challengers had a moment or two, but none of her opponents has yet risen to be the favorite in a very crowded race — and the attacks on her were decidedly muted. They weren’t ganging up on her, and they weren’t making her the issue.