The answer depends on what you're using it for. Silicone is your go-to whenever you're sealing something water-related—bathrooms, kitchen fixtures, bathtubs, even fish tanks. Acrylic is a good general-purpose sealing substance, perfect for tiny gaps between baseboards and chair rails. When still wet, you can wipe away acrylic caulk with some water. However, it dries faster and gets harder than silicone, and you can paint over it.