I would assume that the answer would be Photoshop PSD, But It would just be a biased opinion. What are your thoughts? I recently find illustrator to be fast in position stuff, at the same time my elements are in vector (crisp and sharp). while in Photoshop, as my images/elements grows, my layers also grows and the memory usage grows, Photoshop will then slow down. Making my overall workflow slowdown. So the idea for this is If I have some raster images that needs some Photoshop effect, I will just switch to Photoshop and finish that effect. then switch to illustrator and import that image to my whole design. Maybe it's just my workflow in Photoshop that isn't optimize thats why I find it very inefficient.
I think this also goes with fireworks. I've used these 3 application for web design. I've had long relationship with Photoshop in terms of web design.
Back to my question, what do you usually use for Web Design? and does it affect Designer,Developer and Client in your project?