I'm a 'hardcore' GR 3 user for sure, Revalver is utter crud and so is Amplitube.
GR 3 feels much better to play through more than anything, all my presets are based upon the 'pink numb lead'
It may just be a Rat into a Hiwatt but i use the 'Ultrasonic' cab with this and i get a real nice metal tone.
Sometimes things sound better if i turn off High Quality mode too...
But, here's one to keep an eye on though, Overloud TH1
http://www.overloud.com/found it the other day and i quite like the demo's, '4th generation' modeler or something.
Oh, and if you have Protools you can get one called 'Eleven' which from what i've read should be really good too.