Most definetely something more in the line of a 50mm 1.8G, definetely, my favorite lens for portraits (on DX).
I also started out with a 18-105, but getting into fast primes was very important to me, especially the 35mm and the 50mm. I ended up selling the 18-105, and the 70-300 VR is my only return to zoom lens. Now I wouldn't mind having the 18-105 back, but the time I spent shooting primes only was enlightening, sorta speak.
http://egozarolho.blogspot.com 1. Good content, good aesthetics and good tecnique. On that order. 2. Light is more important than glass and pixels. 3. In the digital photography process, software is as important as gear.