No matter how mainstream deadmau5 or (especially) daft punk, I think they are very good, and Daft Punk is just so special. They do mainstream electronic music that has a surprising level of subtlety if you really pay attention.
Deadmau5 is a bit funny in the way that he went mainstream, but his albums still contain some "raw" tracks that I bet very few can actually enjoy. I think he produces/mixes everything himself, and his sounds makes 80% of the quality of his music.
David ghetta is something else, this is pure fast food music, so if you take it for what it is, i.e. music he barely produces himself (he buys some of them to independent and unknown writers, or associates with people behind the scenes) that is supposed to just hit the clubs for a season, one after the other, then you can have fun with it.