I was never a huge fan of software modeling since I tried it years ago, and everything sounded and felt horrible. Last year sometime I realized that I owned GR5 for years and never opened the program and tried it for guitars, lol. Honestly, I have been pretty impressed with it. I have several very good sounds dialed up on it and it is fun to play.... it is not the flat, fizzy mess many of the programs can be. I really surprised me that I finally started to use it, and apparently everyone else hates it, lol. I have tried some other demos, but have yet to find anything else that I think is that much better, despite the hype online.
I found the #1 key to making it sound better is to use external IRs. I use Reflktor in GR5 to load IRs. Doing this, I think it sounds pretty good overall. I have an Axe-FX II, had PODs, etc.... so I have played a lot of gear.
It definitely makes me want to look int TH3, Amplitube, and some of the other programs out there today. I want to give them a chance, but it is hard when GR5 is basically "free" since I already had it, and I have had good results with it, just messing around.