What is the best roof sealant ... silicone or polyurethane

[@fengdeng1982]

I noticed that other roof repair channels, such as Flat Roof Doctor, use both Poly and silicone for repairs. The results in their videos seem very trustworthy. However, some people say that Flat Roof Doctor is related to or owns the product they use. Therefore, I believe silicone sealant is a more reliable choice. What do you think about using flextape(water proof seal tape) to cover wide gaps, then apply silicone sealant on top? Is that a reasonable option?