I've been trying out Guitar modelling software for so long, and haven't ever found one that I was completely happy with. Guitar is my primary instrument and I've been playing for many years, on and off the road.
 
Last night I installed and played through S-Gear from Slate Digital. It comes with the Everything Bundle so I thought I might as well.
 
WOW.
 
I felt like I was playing through real gear. I've never played through a modelling system that sounded and felt so natural. I went through the MANY presets to start and was so impressed. Each one sounded exactly as it should right out of the box. The response to my fingers and pick were band on. I could just forget the software and play the guitar.
 
The interface is simple, intuitive and functional. 
 
I highly recommend checking this out. I have absolutely no affiliation with Slate Digital, but I just became an even bigger fan!

S-Gear is indeed my favorite...

The effects sound natural, the overall sound sounds natural.

agreed!

S-Gear is my go to amp sim.

How does it compare to TH3?

It's the only amp sim I tried so far that I like 

It's pretty amazing.  I wish he'd work on an AC30!!
 

By far, it's my favorite. It has the best feel to me of any amp sim I've tried.

It's my favorite and it's what I use 99% of the time. I really wish it wasn't hidden. I feel it is better than its competitors, but for some reason it's no where near as well know. Although recently in was featured on Pensados place.

I've used it since it came out a few years ago and it beats all my others hands down. If you haven't got it, try it and you'll be hooked.  Mike Scuffham, the designer, is ex-Marshall (and other prestigious places) and designed the legendary JMP-1 rackmount (I still have one!)