Although composers like Young, Silvestri, Velázquez have had an impressive output in the last 5 years for me, and Tron Legacy is very cool, I would have to pick roque baños' Evil Dead score as it's like a celebration of what I enjoy most about horror scores (Drag me to Hell came close in that department).
If we include (all of) 2008 in ... the last 5 years, my collection has only 20 entries (and these include some TV series); 7 of those 20 scores are from 2008 which demonstrates my feelings towards newer scores.
And there are several among those for which I have little interest (I played Skyfall yesterday but turned it off about 3/4 through ... it was boring me). James Horner's Avatar has yet to click (I do normally like his works) and Hans Zimmer's Sherlock Holmes and Inception have little to attract me. As for John Williams' Indiana Jones and the Kingdom of the Crystal Skull ...
Not helped, no doubt, by my lack of enjoyment of/disappointment in each of the films.
I quite like David Arnold's Quantum of Solace (though I do have to be in the right mood) and both of the Ennio Morricone entries Baaria and Risoluzione 819 are good (the latter being the more interesting for me).
I think I'd plump for a score from a composer new to me, Pascal Gaigne: his Castillos de Cartón is a lovely late evening listen; and his more serious Matka Edeniin is really nice.
I also like Rachel Portman's The Duchess and Abel Korzeniowski's W.E.; Raphaël Beau's Micmacs is good fun, too.
But, to choose just one, I think it would be Matka Edeniin