Oh, I can't just choose one! I am a strong advocate of Daisuke Ishiwatari, so I'll have to post some of my favorites from him. He's done music (and more) for games like Guilty Gear, Blazblue, and the recent Hard Corps: Uprising.
Worthless as the Sun above Clouds, from Guilty Gear Overture. Not a great game, but MAN they got some really heavy s**t. This one in particular stuck out to me right away. One of my top favorites from him.
The Man, also from the same game. I love when they mix stuff like organs with metal. Give this one some time and really listen. It's heavy as hell.
Black Onslaught, from Blazblue. Bad song to listen to while driving if you don't want to arrive at your destination by smashing through the wall and jumping straight out of the roof of the car.
Kill Dog as a Sacrifice to Dog, from Guilty Gear Isuka. NO idea about the name, other than the fact that - to this song - you're fighting a normal dog (wearing goggles) that is piloting a gigantic yeti carcass like it was a mech. But it's not a mech. It's a dead yeti. and he's HARD AS ******** href="https://php8.gaiaonline.com/gaia/redirect.php?r=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DuSdbNjO9erk%26feature%3Dg-hist%26context%3DG20d46f0AHT5IEmQAAAA" rel="nofollow" target="_blank">Feel A Fear, from Guilty Gear X. This song is used for Zato-1, or Eddie as he comes to be called when Zato dies and the shadow demon takes over. Anyway, this one is an old favorite for the dangerous feel.
That's just a few favorites from Daisuke for now, though there are plenty of other games I'd like to cover.