OrdinalChaos check the stats of tools made with those three types of bronze. They are still different enough to be ranked amoungst themselves. 

Different types of bronze produce items with different stats. Broadly speaking, the best bronze items are made of black bronze, followed by tin bronze and bismuth bronze.

- from the wiki (cause this is how I learned about it when I started playing)

Updated to include rationals! Bismuth bronze is very brittle and would most likely not make the best nails and would have to be bigger to compensate for this. Black bronze was in the wrong spot (my bad) but it is only slightly harder than copper. Tin bronze is technically more sturdy than iron but a part of a nails usefulness is its flex which is why I put iron ahead (I am also biased on team iron). Steel is the best because it is less brittle and stronger than iron, but meteoric iron was an insert based upon game progression.

I like it! What's the rational for Bismuth and Black Bronze not being medium quality like Tin Bronze?