I don't see how Sakimoto and Hamauzu can even be compared seeming as how Sakimoto is classical oriented and Hamauzu is impressionistic. They both are quite good in my eyes, although I appreciate Hamauzu more

. The only things I can think that just might put them in the same league is their skill to write and their versatilty.
Sakimoto's most creative works, imo, are Gradius V and Breath of Fire V. They not only had orchestra compositions, but electronica, and even combinations of the two. I am currently hooked to Gradius V at the moment. The compositions are rather catchy and there isn't a single track on the score that I dislike. FFXII seems to be mostly orchestral music, but it just might exceed FFT's brilliance.
Hamauzu is also just as versatile, but with some complexity thrown in. His scores for Chocobo's Mysterious Dungeon, Unlimited SaGa (Disc I), and Dirge of Cerberus all show that he is quite the orchestral composer. But he also knows how to write electronica style music as well. His music from Musashiden II, Unlimited SaGa (Disc II), Dirge of Cerberus, and Final Fantasy X show that side of him. He can also combine styles as heard in the previously listed titles. He has written jazz, bossa nova, rock, electronica, and orchestral. His arranging has also proven successful. Piano arrange albums such as SaGa Frontier II Piano Pieces, FFX PC, and Sailing to the World Piano demonstrate his ability to arrange not only his work but also another composer's music. I find Hamauzu a much more refined composer in terms of versatility and creativity.
To wrap things up, both of them are great at what they do. It is clear which composer I like more, but they have their own unique ways of writing. Comparing their styles is completely unnecessary because they are like night and day.
Jam it back in, in the dark.