I cant answer because every game has a unique feature. and i enjoyed them all. as i love the graphics of Crysis 2.
Love the features in Gta iv. e.g drift, stunts, cops. etc
love the racing in Nfs Run.
Love drifting in Hot Persuit and Carbon.
War in modern Warfare 3.
Concept and story of mass effect 3.
so there is not all in one for me yet