Since the ST has such a low RG Differential, along with a polished solid resin cover + a low RG, nothing in Brunswick's current arsenal would be close to the ST, from what I can see.
The solid Power Groove (teal and purple?), now discontinued, if drilled properly, might have emulated the ST.
Maybe a short pin on a Nemesis, highly polished and drilled to be both low RG (pin close to, but not on the PAP) and low flare, might also emulate the ST. Not sure if it can be done.
The B'wick balls that might have been closer were probably some Rhino Pros from the late 1990s or the Power Blitz Purple from 3-4 years ago, and possibly the Walter Ray Williams MVP ball.
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"...for advice is a dangerous gift, even from the wise to the wise...."
J. R. R. Tolkien