Isn't it great that we have so much choice. I'm a bit like Rain and many other guys here. I have most of the guitar sims and it can be mind boggling. Each have strengths and weaknesses and you may end up finding just a few sounds on each sim that work for you. Or you might have only one that does everything you need.

Every now and then I will go around in circles for ages in Guitar Rig, TH3 and Amplitube, trying to get a good sound and failing. And then I'll remember I have GTR and boom, it sounds great. I actually like the sound of it for cleanish tones.

However, I mainly use it for amplifying synths. I don't know why but it's just great for that. Just stick it on a synth withthe default setting and it adds some subtle grit that doesn't sound too dirty like I find when putting synths through other amps. And it's great for getting a quick and easy stereo sound.

Some of the things in this article (by Anderton) can be a big help using any amp sim.
http://www.guitarplayer.com/miscellaneous/1139/-seven-steps-to-amp-sim-goodness/23054
 
I have AT4, GTR3.5, GR5. Ampire, Nomad Factory Rock Amp Legends, etc.  At different times I favor different sims.  Sometimes I don't like any of them, so I DI my Laney IRT Studio into one of them for cab/mic/fx.
 
IOW, I haven't found anything that works for me 100% of the time.
 
 

TH3 sounds OK as well...
 
Has anybody tried the Universal Audio Guitar Amp Sims.
 
http://www.uaudio.com/uad-plugins/guitar-bass.html
 
I'm no guitarist however I reckon one of these plug-ins will add life to your dry guitar tracks.