Nailing down one style or artist to claim as ones favorite seems nearly impossible to me. I like so many different things. I am personally a fan of a digital illustrator named Chris Nielsen. His work is crazy detailed and looks like actual photographs. He is known for doing work with mostly motorcycle engines and is amazing when it comes to polished chrome. I am so drawn to how clear and detailed his work is. It is actually better than a photography.
Image Source: http://www.vectorvault.com/wp-content/uploads/2008/04/chris-nielson-vectorvault-11.jpg
As far as a traditional illustrator I always think of Mark Bender. I was lucky to have him as an instructor when I attended The Art Institute of Pittsburgh. I always found his style very interesting, and amazing how he would put so many element into each piece, but it all flowed together so well. Visit his website: http://www.benderillustration.com/
Image Source: http://www.pittsburghillustrators.org/portfolios/bender/bender2.jpg
As far as a style goes I am really drawn to the trompe l'oeil technique. For those of you not savvy on the term it is a technique that creates a three dimensional illusion of reality. I of course am not even close to create a good effect, but it is amazing to me that one could study an object long enough and see the detail to recreate a drawing that looks like it could be picked up.
Here are a few cool pieces using this technique.
Image Source: http://t1.gstatic.com/images?q=tbn:ANd9GcS6sktsRvyDM66Gl5mnluXALoytDLKBWiOkTpMqGpGWGhkP1Q4&t=1&usg=__M_lvF-jgjUhDTnSZTLEUSIjYxDc=
http://t0.gstatic.com/images?q=tbn:ANd9GcQG68eq_m-l36r71FUfJa95xV2lRs3aY_Zez22ntkBMnl83iIg&t=1&usg=__7Lw-jIkWleWgSghL-8nj3kbS10Q=
Image Source: http://t0.gstatic.com/images?q=tbn:ANd9GcQkNzSaSeVYxo9oWwmer6qnUXx97_Mrjpx4Elz_TY3EGmZc4kY&t=1&usg=__yXIG08HF6vvfvI2wSOY1cB8pxHw=
Image Source: http://www.lectrics.fr/wp-content/uploads/2009/07/Julian-Beever-ladef-01.jpg
http://www.roadsidescholar.com/wp-content/uploads/2007/10/flat-light-web.jpg