Hmm...well, the best way I could describe SyX is neoclassical/power/progressive metal, but they're much more of a metal band than say, a prog band like Dream theater is (as you could probably tell from listening to Inferno and OSaS). Every member is an outstanding musician, especially their guitarist, Michael Romeo, whos one of the greatest guitarists in metal today, and Russell Allen, the singer, is definately one of the best singers in metal. If you want their heaviest albums, get either Divine Wings of Tragedy or The Odyssey (Inferno is from The Odyssey and OSaS is from Divine Wings). A less heavy and more orchestral album thats also a fan favorite is V. Personally Id reccomend The Odyssey.