No matter what, if it's defined as techno I avoid it like the plague. It's probably some shitty happy hardcore or a repetitive rave.
Electronica is the general term for electronic that doesn't suck (though that's a personal definition.), although Tiesto, Moby and other artists you find at first aren't that great.
Trance? Armin Van Buuren, Paul Van Dyk, Paul Oakenfold for something different (his remix albums before Creamfields are kick-ass). For really good trance (progressive), try Gabriel and Dresden, Oceanlab and Above and Beyond.
Oceanlab:
Satellite [http://tinyurl.com/cutz8b]
Miracle [http://tinyurl.com/b5jsd8]
On A Good Day [http://tinyurl.com/afg3wm]
Armin van Buuren
In and Out of Love [http://tinyurl.com/5rhlbl]
This World Is Watching Me [http://tinyurl.com/7sq8k7]
For Big Beat (in the vein of Fatboy Slim but doubly epic), Crystal Method, Chemical Brothers, The Propellerheads and Junkie XL.
For break/breakcore, Leftfield, Bong-Ra, The Flashbulb, Venetian Snare, Alec Empire, etc. - there's a thread about it somewhere.
Never got into chiptune, it's pretty much remixed MIDI. Sabrepulse is decent, though.
IDM is good too, although when you get into the glitchy sort of artists you're getting into psuedo-trance. Which blows. Autechre is good, but ask someone else about IDM.