How much and what seasoning to should I use in a turkey brine?
Before I try to answer some of your core question with my best from the gut answer, I want to address a bit of an issue with the question itself. Since I am the author of the question and answer upon which you base your question, I feel uniquely qualified to suggest that your source could be a lot better.

The single experiment in that Q&amp;A led to results that were interesting enough (to me) to share. Think of it like the start of a medical study. My fuschia chicken was test subject 0001. To call my conclusions in that answer 'conclusions' is to give them delusions of grandeur.

That said, the next time I brine a turkey (which will not be this Thanksgiving), I will make a basic brine of ~50 grams of kosher salt and ~25 grams of sugar per liter of water (a 5% salt brine). To that, I will add pumpkin pie spice (purchased or homemade).

Why pumpkin pie spice?

Well,


Pumpkin pie spice contains a nicely balanced combination of spices I know to be high in eugenol (cinnamon, cloves, and nutmeg plus ginger)
If I'm brining a turkey, the odds are good that I'm also making a pumpkin dessert so I'm likely to be using fresh pumpkin pie spice anyway.
I'm betting that it will be really good and will complement the traditional Thanksgiving dinner beautifully. I absolutely do not expect the turkey to taste like pumpkin pie.


So I'll add perhaps a tablespoon of pumpkin pie spice per liter of water in the brine, adding it when I bring the salt and sugar to a simmer to dissolve. I'll want the spice quite evident in the brine, but not overwhelming.

If you try it, I'd love to hear how it works for you.

UPDATE 2/15/2020: I just heard from an old friend that she came across this post before Thanksgiving 2019 and followed the suggestions for her holiday. She used 62 grams (2 small canisters) of McCormick brand pumpkin pie spice in "enough" brine for her small (12lb/5.5kg) turkey. It was a hit. No one said it tasted like pumpkin pie spice; everyone said that it was the most flavorful turkey they had ever had. So, FWIW, that's one rave review. I love reports like that!