Unitron
Mushroomhead's always been one of the most interesting bands in my opinion, there's really no other band quite like them. You can hear where their influences may have come from, but they craft their music in such a way that I've never quite heard before.
A clear point of reference is Faith No More, particularly Angel Dust. The orchestral and keyboard based atmosphere, as well as the vocals bring it to mind. Unlike the transitional album Angel Dust though, Mushroomhead has a much better focus on how exactly they want to sound. There's no awkward deviations, even with the varied range of sounds they have on display. The two vocalists work really well together, the clean vocals sounding like Mike Patton mixed with James LaBrie of Dream Theater if he didn't kill his voice after Awake, while the gruff vocals in a Matt Holt of Nothingface style compliment them well.
Mushroomhead may be the best atmospheric metal band, as they just wrap the listener in this ominous and haunting sound. This is mostly done with the great electro-orchestral and piano work, but it combined with the vocal performances and the rest of the instruments strengthens it. Take the stabbing piano in Chance Sore, the fantastic cover of Pink Floyd's Empty Spaces, or the Kraftwerkian orchestral backing of These Filthy Hands and Born of Desire that sound right out of Trans Europe Express, it's all so good. The best part is that they don't sacrifice any heaviness, and have everything work perfectly together.
One of the most underrated metal bands out there, and one of the best at having a varied approach while knowing exactly how to put all the pieces together.