The best ones imo. As mentioned earlier, most of the songs are really repetitive.
I happen to like Megasound only because it was one of the first hardstyle songs I listened to, and I liked it. I have heard several Headhunterz's songs and they all sounded way too similar... Thus I didn't like them.
Also I really hate when the songs are really long, like 8 - 15 minutes. Makes repetitive stuff even more repetitive with the superlong buildups, short good parts and another even longer buildup.