What is the case for keeping a KYC/nonKYC stack?

Hello. It seems many people treat this topic as taboo, so perhaps someone can point me to the forum/fora where it is better explored and discussed. Could be podcast, or youtube, or blog... I don't know where to research it.

So without trying to pretend I already know: What is the case or scenario which favors

• having ONLY a KYC stack
• having BOTH a KYC and non-KYC stack
• having ONLY a non-KYC stack

?

Another angle on this topic is: For someone who has currently only a KYC stack, why should they consider starting a separate non-KYC stack?

And vice versa.

I am naive about this aspect of btc, and I feel like I need to know more before acquiring more, since it could make a large difference in the future. Thank you.