personally i like DJ Isaac as a DJ
Technoboy as a producer
Titanic, dance pollution, sigma and scantraxx are among my favourite labels.
There is a Hardlife event in Leeds this Friday, one room is Hardstyle/Hardtrance and the other is Techno.

Hardstyle is biggest in Holland (it's birth place), Italy and Germany.
It's popularity is growing in the UK, but Hardhouse seems to dominate the hard dance clubs for some reason.....god only knows why !
Hardstyle is more popular in the North of England and Wales.

Check out www.globalhardstyle.com, it's good resource for all things hardstyle