Every production needs the right beat at it's core. A simple bass and clap just simply won't do. It's something I've noticed at the heart of all my favorite tunes and something I've noticed is lacking in most that do not enjoy. Composition of the right rhythm and production of the right sound for each instrument is key. Most songs have a certain tone or theme within them, I find the best productions have a beat to fit this theme. For example, Crystal Castles samples old 8-bit synthesizers or emulates them; for his beats he uses static noise and retro 8-bit console drum samples to produce their drum kits, instead of using the raw sound of a drum set in his basement. It's just my opinion, but shit needs to match. It's just wrong to have a beautiful and calm melody that you could fall asleep to with a hard club beat behind it.
Following the beat comes the bassline. It doesn't matter whether it's a bass synth or an actual person slappin' that shit, it just needs to carry the song; It has to be powerful. The problem I have with most electronic music, Electro and Dubstep specifically, is when the Producers use choppy bass lines. Sometimes a chopped up, all over the place bass line can work -- Justice is a great example of this -- but most, in my experience, can not get the job done. Some Producers have the talent to produce a choppy bass line that still carries the power of the song, some don't.
Melodies are where the real producing genius comes into play. In my opinion there are no "rules" set in my head for what works and what doesn't. There's no "test" a song needs to pass, no prerequisites to attain for me to give it a chance like with the aforementioned. Creative genius is appreciated and each producer will sound different because of theirs, it's what makes them interesting.
Quick ramblings to get a feel for where I'll be going. In my reviews and postings on Artists, Albums and Songs I'll go more in-depth and elaborate on those three key points above.
Enjoy the Music.