I must admit that as someone who plays guitar I don't really have much experience actually using guitar sim VIs, but strictly from auditioning some of them (via their demos) it seems that while a lot of them sound pretty stiff, there are a few worth checking out:
- Vir2 Electri6ity (& Acou6tics)
- Chris Hein Guitars
- NI Session Guitarist Electric (& Strummed Acoustic)
All of these are Kontakt-based instruments. The Vir2 Electri6ity demos seemed the most natural to my ears, though I don't know how much live playing vs programming had to be done to generate those examples. The Chris Hein instrument includes both electrics and acoustics, though it seems more geared to jazz sounds & styles than rock.
As to pitch bend, I'd be surprised if a virtual guitar didn't respond to MIDI pitchbend, but while that might work for single-line solos, more guitar-specific techniques like double-stop pitchbends (bending a string while holding another string) would require more advanced programming/scripting or a different playing technique, like generating the bend via note velocity (or poly aftertouch, an option I remember from an old hardware sampler I used to have).
If I were looking to choose a guitar VI I'd want to be able to play it myself extensively before deciding, to see if its approach to creating performances suited me, but since these are all large multi-sample libraries that's probably not possible. Again, going strictly by online demos/videos, I'd probably look to the Vir2 instruments as worth checking out, with a lot of useful, natural-sounding articulations..
Btw, since this is not really a GarageBand-specific topic, I'm going to move this thread to Audio > Studio & Recording Techniques.