I was using a Line 6 X3 some years ago until I met the amplitube technology, so I toss off the Line 6. The advantages from emulations is that the software can be upgraded, not that way the hardware, that is limited to the built-in components. Recently, I also got Bias FX and all their libraries like Bias Pedal, Bias Amp and Bias Delay, all them highly customizable but still I like Amplitube because the Fender collection and the general app tone, though it lacks of effects. I hope for Bias Fx to make any update soon and improve the algorithm.
It has a fair amount of compression and top end in it, and it doesn't sound that nice, but it's a cheap and easy option for recording. Also has a tendency to feedback if you try and monitor through its own headphone jack, so you'll have to use USB headphones for that