If you want to play more straight forward metal riffs then EMG's are a good bet - I only started warming to then recently, you won't get much variation in tones and they sound the same on just about any guitar BUT they have their place, it all depends on what you are playing. EG, I find myself reaching for my axe with the EMG 81/85 set quite often when I want to play a really screaming burning hot lead part but I prefer Dimarzio as all rounders. My suggestion to any player is always Dimarzio, great tone across the board.
Dimarzio Evolutions are excellent - check out the Dimarzio site for an idea of what artists use them (Steve Vai among others). Lots of variety of playing styles and tones but they really sound good for tight rhythm and hot lead. Word of warning though, they are exceptionally sensitive (great for sustain and harmonics) so all of your mistakes will sound worse but then again, that is a good thing as it will force you to become a better player! If you want to hear what they sound like in person, go to a guitar shop and plug in an Ibanez Jem (ultra high end axe). Good luck with it and let us know what you go for in the end.