As the above posters have said, I agree with them. There can be instances where one or the other being positive can workout for the benefit of the company. However, making that choice without knowing company culture, project projection, the budgets, the timelines, what the product is, etc., can be a tough choice to make.
For instance, if I was in a large company that had a larger budget, I would rather have positive SV because their goals might be to have more products on time, even if they go slightly over-budget. On the other hand, let’s saying that I am an aspiring entrepreneur, I might be okay with a negative SV because my budget might have no give at all. It really depends on what you’re working with and what you are willing to sacrifice.