Froome said the low point of his Tour was when he ran short of energy on the second ascent of L'Alpe d'Huez this week.
"A horrible feeling," he said.
The highlight, he said, was when he powered away from his rivals on Mont Ventoux in Provence and became the first yellow-jersey wearer to win a stage on that mammoth climb since the legendary five-time Tour winner Eddy Merckx in 1970.
"That was an incredible moment, incredible."
Saturday's stage did a big loop south of Annecy, through the mountains of Savoie between the lakes of Annecy and Bourget. This is cheese-making country, with lush Alpine pastures and dense, naturally cool forests.
Quintana's win also secured him the spotted jersey awarded to riders who harvest the most points on mountain climbs. He also retained the white jersey as the Tour's best young rider. The 23-year-old wiped away tears in his stage winner's news conference.
"It was fabulous," he said after winning on his national independence day. "It's a very special day in Colombia. A big party and the whole of Colombia is celebrating."
With six miles still to ascend on the last and toughest of the day's six climbs, Froome put on a devastating turn of speed that left Contador gasping. Froome, Rodriguez and Quintana then rode as a trio, leaving Contador further and further behind. Quintana rode away in the last stretch for his first stage win at his first Tour.
Contador placed seventh in the stage, laboring in more than two minutes behind Quintana. The two-time former champ ran out of legs after weeks of trying to keep up and pressure Froome. He dropped to fourth overall, more than seven minutes behind the Briton who was born in Kenya and who hopes his win will inspire African cyclists to believe that they, too, can turn professional.
Of the 198 riders who started on the French island of Corsica on June 29, 170 have survived this far — meaning they could equal the Tour's record for finishers, also 170, achieved in 2010.
Uniquely for the 100th Tour, Stage 21 will set off in the late afternoon, so the race finishes more or less as the sun is setting behind the Arc de Triomphe.
"The arrival on the Champs-Elysees will be immense," Froome said.
Froome said he didn't know how many more Tours he might win because "I'm just thinking about here and now" but he added that he would like to keep coming back to the Tour "as long as I can."
Froome was runner-up last year, helping Wiggins to victory. Despite that, Froome said his teammate hasn't contacted him during this Tour.