How much quantitative analysis skills is enough for a PManager?

None. You can manage risk without performing quantitative analysis. First of all, you have to define your Project risk management process where you could have or not have quantitative analysis defined as one step. Second, the project manager will not perform quantitative analysis, the SME (subject matter experts) will perform it.

I am more aligned with Sergio's opinion. The knowledge in PMBOK is enough. Otherwise only basic high school skill is adequate here. Anything more than that the PM can ask expert advice.
The exception is that the role requires more skills than a generic PM, then it is a different question.

None. You can manage risk without performing quantitative analysis. First of all, you have to define your Project risk management process where you could have or not have quantitative analysis defined as one step. Second, the project manager will not perform quantitative analysis, the SME (subject matter experts) will perform it.

Well, "better" is an ambiguous word each person needs to clarify before accept it. I mean, "better", "worst" are subjective matters terms that have to translate into objective ones. My background gave those skills to me but if you ask me how many times I applied it when performing Project Risk Management in projects I will say no many times. I have applied it when I worked in environments or domains where they need to be applied like finance (sometimes depending on finance business) or science. The project manager is not in charge to perform activities related to project risk management like quantification or qualification, the subject matter expert/s are. So, what a project manager has to do, is to adquire knowledge to understand the stakeholders but not being an specialist.