Which factor was most at stake for both unionist and secessionist in south carolina

It was mostly about wealth. Without slavery, the southern prosperity would end. The unionists wanted to remain in the union but were not completely prepared to abolish slavery, while the secessionists demanded a clear separation from the union and an establishment of an independent confederation of southern states if others were willing to join them. Not only would they lose wealth, but also political power because the state would become a lot weaker. They would lose much more than they gained in both ways so it was problematic.

It was mostly about money and wealth. They lose wealth and power because it came weaker as their power degrades. The problem of this is that they lose much more than they gained in both ways when they wanted to remain in the union. They were not completely prepared to destroy slavery, while the secessionists demanded a clear separation from the union and an establishment of an independent confederation of southern states if others were willing to join them. 

It has the potential to lead to limits on rights by giving flexibility in making laws.

And this too use this if needed