I really think that our 2012 side was one of the best ever and that it really underachieved.
It was well-balanced, with two excellent players for every position. It had one of, if not the best defences and scored plenty at the other end. It also knew how to win the big games; our record against the top 6 that year was excellent. And what many people (especially the detractors who accuse us of 'limping' over the line) forget was that we beat an exceptional Utd side that year (they amassed 89 points and finished second, after all, and then went on to walk the league the following year simply by adding Van Persie).
Aguero, Tevez, Dzeko and Balotelli - has there ever been a better roster of strikers? In Kolarov, Clichy, Zabba and Richards we probably had four of the best five full-backs in the league that year.
I think it's because that it went down to goal difference that people overlook how good that side was. Our European campaign probably hurt its reputation too. But just looking at PL performances, I can only think of the Utd treble-winners and the the Arsenal invicibles as being better. Chelsea under Ancelotti were also excellent but they lack of decent competition makes it hard to judge that side.