The 33-year-old was one of the spearheads behind an amazing recovery last term, when the Black Cats put together an unlikely run of results to retain their Premier League status.
The defender collected five Premier League titles during his spell with Manchester United, but he revealed that avoiding relegation at Sunderland was an equally satisfying achievement.
But he is determined not to find himself in the same situation next season.
"You don't get any medals from climbing away from the foot of the table, but I was asked how the feeling we have at the moment compares with collecting a winners' medal," he told the club's website.
"Undoubtedly the elation we are all experiencing has got to be up there.
"The achievement is all the more satisfying because of the teams we have had to face in recent weeks and the pressure we were under when we were written off.
"We have stood up to it and, after last season, we are already thinking about making sure that next year, we start off much better so we don't find ourselves in the situation we have just come through."
Sunderland turned their season around when they collected four points from trips to title contenders Manchester City and Chelsea before victory at Old Trafford and a home win over West Brom secured survival.
Head coach Gus Poyet replaced Paolo Di Canio in November, when the club were bottom of the table with just a point from seven games, and O'Shea paid a glowing tribute to the Uruguayan and his staff.
He said: "We took only one point from the first seven games so right from the moment the gaffer came in we have been chasing teams.
"But it's to the credit of the head coach and his staff that they have stuck to their guns in terms of how they wanted us to play.
"They have got their ideas across about how they want to see us create chances, and so credit is due to them as well as to the players who have worked hard to put these ideas into practice."