Techno is used too widely.
If you want techno go for Carl Cox, Tom Harding, Mauro Picotto (That stuff)
(Mauro Picotto - Awsome)
Tiesto is a trance/progressive trance DJ/Producer
He was voted for best trance DJ last year.
He has also made some really good stuff:
Dj Tiesto - In my memory
Dj Tiesto - Suburban train
Dj Tiesto - Sparkles
Madonna - Die Another Day (Tiesto's Dedicated Mix)
If you want more really good trance artists check out:
or more Hard Trance artists:
here is some good trance compilations:
In search of sunrise
In trance we trust
Gouryella - Ligaya
Sunblind - Believe (Nu-nrg remix)
is on top of my "25 most played" in iTunes.