That's the odd thing with amp sims, they are very personal. You can get a usable tone with pretty much all of them, but what makes them click for some is very subjective.

Right now my favorites are the 3 free amps from Mercuriall. Those are the most organic sounding ones. Something in how the low end moves is just like a real amp to me.

Right behind them are the Mesa, Orange, and Marshall models from Amplitube. Killer sounds from those. I don't use the cabs from Amplitube. Favorite IRs are from Gods Cab, and they have been working for everything right now.

I was really impressed with Schuffam, but for some reason never kept using it.

Then I group Lepou, TSE, and Joey Sturgis sims all together. Lepou used to be some of my favorites actually. But they all seem a little static compared to the others.

Gonna give that Blue Cat plugin a shot. Seems interesting.