If we're really talking MUST have guitar software, then either Tonex or NAM is all you need, since those are simply the most realistic soundwise. Modulation effects such as delay, pitch shifting or reverb can be done by non-guitar software.

 

No software that I ever have used in front of a guitar can for me replace an amp pushing air...though the Strymon Iridium for whatever reason worked well enough for a time until it didn't please sonically any more. What I have though enjoyed while using it for that time was finding it's sweet spot before breakup and rolling my guitar's volume knob to keep it dialed in there or digging into the strings when I wanted to growl. Now I just use my little AC4TV and pedals.

 

your exactly right about dialling in a sweet spot, if you can with sims its better then captures themselves,

NAM Tonocracy tonex all offer captures with some ok decent interface to tweak but you can't tweak them like real amps where you dial up, roll back away from breaking up to find that sweet spot, you can how ever with Howard Benson, with Jeff Loomis and with Kuassa and very few others, softube with Ik Multimedia at the bottom,

Ik multimedia made zero implications of the marshal actual characteristics, there is no special type marshall interface with channel splitter master vol, contour, as some have some dont, instead IK etc slap colours and shapes to appear as Soldano, Peavy, Marshall Vintage or modern ect, unlike Neural DSP, Howard Benson, JST Jeff Loomies, and many more who add switches and optional functionality so the amps behave like the real thing.

 

I'm not a guitar player, but I really like the sound of Softube's Bluesbreaker. And IMO TH-U sounds 'more real' than Amplitube. I have used these both with Ample Sound and DI live guitars. And, in general, using Reaper's parameter automation LFO subtly on some effects parameters seems to bring things to life a bit more as well.

 

How 'bout this?

 

I think this guy is good with marshall info