"I see it in this order: Vettel, Alonso, Button and Hamilton," he told the Italian sports daily La Gazzetta dello Sport.
The F1 chief executive said he was curious to see how Mercedes' sweeping changes for this season will make a difference, and said McLaren has a "better chance" to win the 2013 title compared to last year.
"Many will not share my opinion," said the 82-year-old Briton, "but I think McLaren is now better balanced and Button has the potential to be even better."
Ecclestone also expects a good season for Ferrari.
"Ferrari will be strong, I have no doubt," he said. "But they need to start well -- they can't wait for five or six races and then emerge," added Ecclestone, referring to Ferrari's poor start to its 2012 campaign.
He also did not sound sorry that HRT has folded.
"In Formula One, there should only be the best, not teams that have difficulties," said the F1 'supremo'.
"I think there should be ten teams at the most. It's the ideal number to manage the championship well."
Meanwhile, having officially confirmed the Nurburgring in its July 7 calendar slot, Ecclestone admitted turmoil behind the scenes at Italian grand prix host Monza.
Recently, amid a management controversy, the historic circuit's chief Enrico Ferrari was stepped down.
Ecclestone admitted he doesn't "understand what's really going on", but praised the departed Ferrari's role.
"Thanks to him, Monza had a favourable economic treatment compared to all the other European races," he said.
"On the continent, no race is as cheap as the grand prix of Italy," Ecclestone reiterated. "He was tough in business, but competent, straightforward, clean."
Ferrari's successor is Fabrizio Turci.
Ecclestone said: "I do not know and do not envy him. Without Ferrari it will be more complicated, because Enrico was a key man."