I would get the mark V. Its so underrated its mind blowing. Ive had over 30 high gain heads since the late nineties and of all of them the only one I would buy back without question was my mark V. It was just so versatile. The only thing that I disliked was that when playing a mark V has its own vibe that cant be dialed out. Some love it, some hate it. You can get it to sound close to other amps but it always sounds like a mark V trying to be something its not if that makes sense. Right now Im playing an EVH 50 watt and absolutely love it but I would be lying if I said I didnt miss the V every now and then. The IIc+ setting can really get you into justice territory and the IV IMHO sounds better for black album stuff. If you want pre justice tone then you might be looking at marshall style amps. I have never played the VH4 or any diezel for that matter. But no matter how good it sounds that is the new sound of metallica. And even then i hear James uses a blend of a few amps to get his tone.