The strength and rigidity of the bill material you choose is what's most important. Ideally it would be super thin, so the bait dives more quickly because of less water resistance from the edge of the bill, very rigid, so the energy of the water flowing against it on the retrieve isn't lost or lessened by the lip bending on the retrieve, and super strong, so it doesn't break or crack when it hits something, or, like the older Rapalas, when you slap grass off of the bait.
For me, there is no one perfect material.
I have had to play around with different materials to find which ones work best for which baits.
I use circuit board material for baits that don't have the line tie in the bill, and Lexan for those that do.