Here's the comparison:
Nidoqueen:
Pros:
>1. A good defensive Pokemon
2. Has a good defensive typing
3. Poison type gives it an edge against many fairy behemoths
4. Has access to support moves like Toxic Spikes, Roar etc.
Cons:
>1. Weakness to many commone types like water, ground and ice.
2. Outclassed as a wall
3. Not overall great defenses
4. Limited coverage as an attacker
Nidoking:
Pros:
>1. Has a boon in the ability Sheer Force, which turns it into a fearsome attacker
2. Does not suffer Life Orb recoil
3. Poison typing helping it against many fairies
4. Solid offensice movepool
5. Completely viable running a special set
Cons:
Mostly the same as Nidoqueen and also the fact that it gets very little advantage from it's low special attack stat.
My Opinion
Nidoking is superior.
This is because it is more concentrated into side, that is offense. While Nidoqueen is a good wall, it is outclassed by many Pokemon like Weezing, that do it's job much better.
Hope I helped!
