Guitar Rig looks popular. You will get a whole host of Amps and Stomp box effects to use in there. I know for guitar there are a few cool options you could look at. Waves Guitar Rig, Line 6 Pod Farm, IK Amplitube and I am sure others. I use Pod Farm for my guitar, and it is all over my tunes in ableton as well now, if I could just find my codes to get all my stomps again since a computer change I would be in heaven. Everything from your bog stadard Tube Screamer models, through to De-Essers, Comp, Reverbs, Delays.
All of them are upto a pretty high standard these days on re creating the sounds. My guitar sounds real good through it!!!