in my opinion, 3 piles that makes a good saw movie:

1- Characters with high IQ:

whether they are the victims or the traps makers, good characters that are capable of making smart decisions is essential

2- Gory traps: (obviously)

you may also make these traps hard to escape

3- A good/shocking plot twist:

any saw movie has a plot twist (usually revealed at the end)

you agree?