The Lord of the Rings scores are pretty iconic and I think Howard Shore created some very memorable melodies and a very distinct theme that will be identifiable with that franchise for quite some time.
I know some people might not enjoy them as much as Danny Elfman's scores, but I've come to appreciate Hans Zimmer and James Newton-Howard's collective work for Nolan's Batman films, especially their score for The Dark Knight where I felt like they really nurtured, progressed, and evolved the themes from the first film. I can't tell you how many times I've put the Dark Knight score -- and by extension Zimmer's Inception score -- on continuous loop.
I really loved Michael Giacchino's Star Trek score. Especially his complete, expanded score that he released earlier this year. I thought it was fantastical and epic and grandiose just as Star Trek should be. While I felt it definitely embraced its fantasy side more than its science-fiction side, I still thought it was a worthy successor to the likes of the compositions that Courage and Goldsmith have done in the past for the series. I think if Giacchino gets the time and opportunity to nurture his themes and motifs his work could be as revered as either of those composers' contributions to the franchise.
Also, I love John Williams' score for Harry Potter and the Prisoner of Azkaban. I guess I'm biased because that is also my favorite film in the series, but Williams really delivered a fantastically quirky, fun, dense work that I've enjoyed many listens.
Clint Mansell's contributions to the science-fiction genre also need to be noted. I absolutely adore his emotional and poignant score for The Fountain as well as his understated score for Moon. They may not be as bombastic or as instantly memorable as any one of John Williams' compositions, but they are extremely infectious and noteworthy pieces of music that are really affecting and moving. Sometimes I'm not in the mood for a bombastic Williams score; sometimes I want moody and heartfelt music and composers like Mansell deliver that in spades.
Also, I can't leave this post without mentioning Bear McCreary's contributions to the science-fiction music world. His music for Battlestar Galactica is unanimously epic, heartfelt, genuine and soaring all at once and he has been the best composer since Brad Fidel to make the Terminator music work as displayed in The Sarah Connor Chronicles (probably because he had more of an opportunity and chance to expound on Fidel's original work, whereas other composers like Marco Beltrami and Danny Elfman each had one film).