"I've said a few times already, I think it'll have to go together with 2012," he said.
"I consider this my best season ever, better than 2005 and 2006 for sure, even if it was the championship years.
"I think the level of performance, consistency and extracting the maximum of the car, I was very happy with how I connect with the team and the car.
"Just enough to finish P4 in the championship. A little bit unexpected, I would not put any money on Thursday on myself finishing fourth! But here we are, it's like a gift to finish in front of the Ferraris and Lando [Norris]. We take it."
The two-time world champion also looked ahead to the 2024 season, claiming that the team's performance shouldn't be a surprise anymore.
"It's going to be a much better winter," Alonso added.
"Once you get rid of the seat fitting, controls, accommodation of your wishes, putting a face and name to everybody in the team, that drains a lot of the energy already in the months of January and February.
"I think next winter is going to be a little bit easier for everybody to transition from 2023 to 2024. High expectations as I said, it's not anymore a surprise if we are on the podium.
"We need to deliver that kind of performance next year and we're ready for the challenge."
Following the demanding schedule of the 2023 season, which featured a record number of races on the calendar, Alonso emphasised the need for rest before thinking about the upcoming season.
"I am excited, but I'm very tired from this year!" he said.