14-15 was a "conventional" world-class team, but not very special in terms of actual domination of the match. We simply went toe to toe with teams and blasted them away with the tremendous firepower we had, supplemented by great seasons from Alves and Iniesta in particular. Not that much different than best versions of Madrid, Bayern, Liverpool.
2010-11 was the most advanced version of Pep's "Juego de posicion", crazy stuff but totally unsustainable for more than one season. 2008-09 sits somewhere between those two. More structured and clearly more dominant than 2014-15, but not quite as commanding and fluid as 2010-11. Had some stronger leaders though, like Eto'o and Puyol, still in their prime.
2011 on the other hand had the peak of Xavi, Iniesta, Busi, Messi, Alves. But they did lack at times the blunt presence of a physical, fast, killer like Eto'o was. Can't have it all I guess.