Go'ol Macromedia Freehand 10. Beats Illustrator (not even comparing to Inkscape

) in drawing time 1:2. Especially for vector art, copy-paste-inside is irreplaceable with Illustrator's masking crap.
Sketching of 3D in Sketchup (not free, I use the commercial one, as I need 3D export).
Photoshop I only use for preparing tracing files and making gradients, which I again paste into a vector shape in Freehand. If you want gradients super-fluent, Freehand and Illustrator are amateurs.