Wizard would be your best bet, the advanced progression is huge, has several advantages over the Arcanist features with the right school choice, and Arcanist boosting Save DCs and CL, the biggest attraction to their spellcasting, doesn't help a whole lot here. Note that being Human, I highly recommend the Dimdweller racial trait, which gives you Darkvision 60' in exchange for your free skill point; having high Intelligence and potentially Favored Class Bonus, you can easily get by without an extra skill rank per level.
The biggest problem is that several Shadow/Darkness spells are scattered all over the place in terms of spell schools. The biggest set of them are Illusions, followed by Conjuration and Evocation, and then some minor (but powerful) bits in the remaining schools. This can be a problem starting out, but with proper spell planning, you can make it work. As such, you would want to make Enchantment and Necromancy your opposed schools, as they have the least Shadow/Cold spells while not having the versatility of the Transmutation or Abjuration schools.
Also keep in mind that a lot of your spells may not work on certain enemies, such as using Darkness on enemies that have Darkvision, Deeper Darkness (which you wouldn't be able to see through in certain conditions) on enemies that have the See in Darkness ability, and so on. They do get some interesting metamagic feat options though (such as Heighten to counter those enemies with Daylight spells/SLAs), so I'd look into those for bonus/regular feats and see if they can help your viability.