I've been through too many metal type pedals. Some were bought, some are kept & others dismissed even before purchase. BOSS' Metal Zone is arguably the standard reference when this metal business comes to mind. I'm not going to mention it here because that one is a proven worth. The current breed of players are into other avenues of intense distortion reference. Thanks to the stores here, we have a healthy selection of such distortion to choose from.
My flak with many of them is the fact that I have to reinforce the saturation on board with another pedal. This is sheer proof that the pedal concern is lacking in this aspect. For a good reason, we believe it was intentional. On the flip side, we know there's a lack of consideration for this. Let's face it, some manufacturers are not good at giving us a convincing metal type distortion, it's just not their thing. If you are in for such a pedal but wouldn't want to spend excessively (you're not the boutique type), I have two recommendations for you. These are metal type distortion units which are self-sufficient in terms of both saturation & intensity.
1. Blackstar- LT Metal
This is Blackstar's subsequent pedal range where things are trimmed down in terms of circuitry; no tubes on board unlike the initial HT range. There's more than enough intensity in this one & it's largely pick-sensitive. The strength of the LT Metal lies in the ISF & Tone controls. To sum it up, the ISF offers you a voicing variation (American vs British) & the tone control focuses on EQ.
2. EHX- Metal Muff
Electro Harmonix had been on the fuzz forefront for too long before the Metal Muff showed the world what the manufacturer could do in this aspect. The catch here is that the MM has a trace amount of fuzz to it which is a like/hate affair with players. I personally like this pedal for its sheer intensity; it sounds like an angry amp rather than a polished pedal-type offering. The 3-Band EQ means you can vary your voicings to taste. The top boost here, according to the manufacturer, aims to enhance the upper frequencies when you solo. What I hear in use is very much like cascading intense distortion into a treble-rich light overdrive unit, in this case, the Klon Centaur would be a good reference.
I own the pedals discussed here & they are my go to reference when comparing others of this ilk. Some boutique units are out there to stroke your ego more than getting the job done. My advice is for you to try them out because in boutique territory, it could be an expensive mistake.
Blacktar's LT Metal & EHX's MM are both available at Davis GMC.