PS is the one for me, working in the magazine/repro/graphics field I can tell you that the Mac platform is still the dominant platform thats why photoshop is the main man and not paint shop pro.For pure raster image work I use PS cs2, the new smart objects function is lovely, for single page text layout it is illustrator and for mutli page spreads quark or indesign or if feeling a little adventurous macromedia freehand.
preferred file formats EPS, tiff, psd or Distilled PDF(pass4press job options or press quality).