Since favorite doesn't always mean the absolute best, I'll name some of the people who really interest me.
Hitoshi Sakimoto - My singular favorite VGM artist if I had to pick only one. I know some people accuse him of repeating himself and sounding generic, but I think that's not quite fair, since he normally tries to throw in some twist if the game allows. See Soukyuugurentai, Vagrant Story, Legaia II: Duel Saga, Breath of Fire V, Gradius V, or Lord of Vermilion II for just a few. He is very diverse when he's allowed to be and I think he has untapped abilities still left.
Hayato Matsuo - My favorite orchestrator I've ever heard. Whenever this man gets an orchestra he crafts the kind of rich, thick, sophisticated sound I want to hear. See the Panzer Dragoon vocal pieces, his arrangement of "Radical Dreamers" for A Night in Fantasia 2009, or his own song, "Sonatina of the Breeze" for Magic Knight Rayearth, and his synth stuff still retains much of the depth. He also makes some pretty bizarre, crazy funk music, as Blitz Lunar mentioned with Syvalion. I am of the belief that he is such a pro he could do anything if asked.
Hajime Wakai - Sounds kind of similar to Matsuo, so it was as if they had asked me personally my wishes when Pikmin's "A Panoramic View" was arranged by him for Symphonic Legends (it turned out perfect). I really enjoy his Star Fox 64 and Pikmin sound. Haven't played Skyward Sword yet but I hope the music is as good as I want it to be.
Miyoko Kobayashi - We all know Terranigma is fantastic, and her Granstream Saga music retains the quality. She has a really special sound I wish could be heard more often.
Saori Kobayashi - Ditto for the other Kobayashi, but substitute Terranigma for Panzer Dragoon Saga and Orta. Also "If I Run With You I'll Cry" from Sakura Note makes me wish she'd arrange a whole Uematsu soundtrack, since I think she could bring something more distinctive and creative than his usual arrangers do.
Tsuyoshi Sekito - The Last Remnant and Gyromancer are good stuff. I think he and Yasuhiro Yamanaka would be a good choice for arranging an Uematsu soundtrack as well, seems they'd be a good fit.
Masashi Hamauzu - I was certainly not a fanboy as many people are; SaGa Frontier II is too long and repetitive without enough standout tracks, I do not understand what is supposed to be so special about his piano arrangements to make them better than anyone else with some skill, Dirge of Cerberus would be great if it actually had more than about six melodies over the course of 2 hours, etc. But Sigma Harmonics was a good sign and then Final Fantasy XIII did exactly what I wanted it to do. I do appreciate his distinctive kind of sound, especially when he applies it on tunes as good as FFXIII has and I look forward to new works from him.
Koji Kondo - Please write more music! We took you for granted when you were
the composer at Nintendo because you could always be relied upon to write sheer greatness every time. You make it look effortless and once you hear other people doing Mario and Zelda music and it most of the time just isn't the same, we can see it's not so easy for most musicians.
I could go on but I should stop, I reckon.
