I donno man, I've seen Designer Drugs open for a bunch of people (deadmau5, flux pavilion, doctor p, a show on their own at lincoln hall etc) and they're not very good IMO. I love A-trak though! One of my favorite DJ's to watch live. Mostly all of his good songs are remixes, but they're awesome. I agree on Justice too.
The people that said Deadmau5 must have not been listening to what he has put out this year so far... that 4x4 garbage.. jeez.
I don't know. in no specific order I would have to say...
Chemical Brothers
Daft Punk
Justice
Bassnectar
and I'm gonna go ahead and throw SKREAM in the mix. Hands down my favorite dubstep producer. I wish more people in America would listen to him and give him the respect he deserves.
I would also love to put in Underworld and The Prodigy but I guess its only 5.

It took me almost a half hour of listing and erasing names to come up with this list.. lol Goodnight guys.