That's a matter of personal preference. Their moves are similar and their stats are exactly the same. A-Muk trades a psychic weakness for a resistance, but it loses its fighting resistance. One of the main reasons to use regular Muk was to slow down a Machamp, A-Muk gets steamrolled just like anything else that doesn't outright resist fighting..
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Should I max out Muk or Alolan Muk?
Which is the best Poison-Type, Muk or Alolan Muk?
Edit: Do you know something? Don't even lose your time ansewring this question. I will just wait for Gen 4 to evolve my maxed out 100% Roselia into a Roserade.
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Identical stats and, with the exception of legacy moves, almost identical movesets. A-Muk being part dark, it gains a resistance it's Kantonian counterpart doesn't have. However, psychic is an irrelevant weakness, and being part Dark means it loses Poison's only relevant resist, Fighting.
It does get STAB Dark Pulse tho...
Let's think about the question for a moment.
Why raise any form of Muk to begin with? Well, one of four reasons:
1: for defense
2: for raids
3: for gym attacking
4: for fun!
For point 1: as of right now, normal Muk has the crown due to Machamp, though Alolan muk is not "bad" as it's a better answer to most Mewtwo variants.
Point 2: there is only one real reason to use Muk in thr first place: SE damage. Poison does SE damage against 2 types: Grass and Fairy. Of those, the most notible is Fairy due to its lack of good counters. Based on this, Muk will generally be better due to its outright resistance to Fairy, while Alolan Muk's dark type makes it neutral. However, depending on the moveset, Alolan Muk may fair better, as I will discuss next point. Against grass types, we have an issue again. This is mainly in looking forward, but one of the biggest grass types on the way is Virizion in Gen 5, who is part Fighting. I don't think that I need to continue on that point. On the Dark side of things, Alolan Muk has some issues once again. As a dark type attacker, Poison is a liability. It weakens the resistance to Psychic types and is of no use against Ghost types. Its only niche is against fighting movesets like Focus Blast on Gengar or Alakazam.
Point 3: On gym Offense.. who knows? Despite all of the guides, gym defense doesn't just consist of the main defenders like Blissey and Snorlax. You will find a TON of random mons, some of which Alolan Muk will better handle. However, one particular match up does come to mind (as alluded to in the previous point): Gardevoir. Alolan Muk is a great counter to Gardevoir. It resists Confusion, resists Psychic, and resists Shadow Ball. Normal Muk may have an edge Vs Dazzling Gleam, but keep in mind that it'll be eating Confusion before that ever happens. If we ever see a Gardevoir raid, Alolan Muk will likely be a noteworthy counter, while Muk doesn't even get a mention. The only other SE counter to Gardevoir with a similar resistance profile is Scizor with dual-steel, and Ghost has nothing noteworthy due to Gengar's weakness to psychic moves.
Point 4: do whichever ya like better!!!
Note that these points all ignore more optimal counters and counters of other types. I was JUST focusing on Muk and Alolan Muk. And despite all of my side-glances to Alolan Muk, I am raising one as soon as I hatch a decent Alolan Grimer. I follow the school of thought that says I freaking love Alolan Muk =P
I always liked Muk. His rarity is one of the reasons I liked him so much. Before raids and rare candies, not many people had high level Muks. I had 2 high level ones, one for offense, one for defense. I used him a lot as a generalist. He was bulky and poison wasn't really resisted by defenders. His one downside was a lot of defenders have psychic moves. Because of this, I would go with Alolan Muk for attacker because you get that resistance. Sure, as you mentioned, he doesn't resist dazzling gleam, but he also isn't weak to it, which is important for a generalist. I think the clear choice is Alolan Muk on offense, and he is fun to use.
No offense, but Muk's a poor man's poor man's generalist. It's outclassed in that role 9 times out of 10 by non-legendary generalists like Dragonite and Salamence, which themselves are outclassed by the Legendary generalists like Rayquaza and Mewtwo. Unfortunately, there are only two arguments for either version of Muk that hold water in terms of strategic uses when compared to other investments:
1: specific niche fulfillment
2: lack of available resources.
My argument focused on the first, as neither version of Muk is strategically worth investment as a generalist given ANY potential to invest in a more suited generalist. On top of that, most of my arguments looked at Muk in a vacuum, where its only competition was its other version. In most cases it's outclassed by specialists of other SE types, with the possible exception of a Fairy counter... for now.
That said, I've seen the video of a guy using a Rattata against all *1 raids and winning. Was it fun? Heck yes. Does that make Rattata the optimal counter to all *1 raids? Heck no. I'm glad that you like Muk and have had a good time using it. Heck, I love Muk and, as I stated before, I will be raising an Alolan Muk as soon as I get one that's worthwhile. However, there's no denying that 95% of the things that the two versions of Muk can do, some other Pokemon can do more efficiently. I'm simply arguing the point of the topic: which has the stronger niche?
EDIT: Okay, I will concede two points on Alolan/Muk's behalf as a generalist on thinking about it a bit deeper:
1: While its attack is too low to be great, its DoT is solid, which makes both versions decent in terms of potion-efficiency.
2: Alolan Muk's single weakness to Ground, which is VERY rarely seen, does allow it to sit through more 'mons without switching than most. Though I sort of touched on this in my original post when I pointed out the potential diversity of defending 'mons.
