Paul Murray
Ultimate Member
I've been using Sketch for about a year as an alternative to Photoshop for web and interface work. Photoshop is nice for pixel-perfect work but using it for interface design is really a bit of a hack, and I could never seem to get used to Fireworks. Sketch is kind of a mash-up of all three, but it's specifically intended for screen-based design work. It's not quite 100% there yet and is still lacking in a few places, but it's served me well for a little while now, and can export your layer styles as pure CSS!