I recommend downloading some sets by them

Bas & Ram are known for their special style of hardtrance, they have been big from the Amsterdam scene for at least the last 5 years or so.
Alpha² are upcoming talents (they were 17 when they started), they spin like crazy and prefer tough hardstyle in the likings of Activator.
Vince is a hardcore DJ, I don't know much about him and never sam him play before but he has some years of experience behind him.