Whichever one you choose, I don't think there's a "correct" mannequin for a gesture. If you build your gesture on a line of action you can use almost any shapes / forms you need to get you to the finished product.
Personally, for my own creations I prefer to use something like moderndayjames' form primitives because they help me understand the 3D forms of every mannequin part, but if I were to do a drawing from life I'd probably use Youssef's process because it lets me silhouette out the major body masses and carve them into 3D forms after the fact. Form blocking in 2D shapes is very powerful for translating a reference onto your page.
I'm currently going through Michael Hampton's figure drawing book because I want to build my anatomy study progressively with each body part being added in a compounding way with the others. I've done lots of individual body parts studies through sources like the Taco books I referenced and the Morpho books, but I find studying the body masses the way Hampton presents them helps me to build a progressive model where I know how to get to the other muscles from any adjacent muscle.
The mannequins you use to study something do not need to be the mannequins you use and you don't need to use a single mannequin. You can explore mannequins through a silhouette where you do one big form blocking process on your page and carve it out into 3D shapes later. The form blocking through a silhouette lets you conquer the total 2D presentation of your character first and then making that 2D shape make sense in all three dimensions later. That's partly how Youssef's gesture works and that's also something Blaise recommends in his creature design course.
There is no one way to do gestures, there are only ways you find the most helpful to solve some problem on your page.