I haven't used that amp, but I would suggest that instead of diving through hundreds of presets, start out with something very simple. My rig is an old Eleven Rack and I use pretty much two amps for guitar. One is modeled on the '65 Super Reverb. I usually pair it with a 4x10 cabinet, which is how the Super comes. I have a real Super sitting here, although it's an early 80's silverface. To my ear, the 11r and the Super sound very much alike. You might also try the '65 Twin that's in the GTX, along with a 2x12 cab. Those and the early Fender tweed are pretty much the source material for what came later.
I also use a JTM-45 model with a 4x12 Celestion Greenback cabinet simulation. I don't have a Marshall JTM-45 to compare it, but that's the one I like most.
Your tastes may vary, but pick a couple of the amp sims included and concentrate on those. You will eventually start to figure out what you like and what you don't like.
The only other amp sim I use is the Ampeg SVT with an 8x10 speaker package which I use for bass. I haven't found anything I like better.
Then try the basic pedals. The Greenbox in the GTX, which is modeled after the Tube Screamer, the Blackbox, modeled after the Pro Co RAT. Fender doesn't identify one as being a Boss Blues Driver clone, but they have a variety of different OD pedals you can try.
There is enough to keep you busy for quite a while in the GTX50. Take your time and find your own sound. IMHO, the presets can just confuse the crap out of you. Find your own sound instead of trying to find one that's good enough from the presets.