STO was popular for a couple of months but then came IEOs which completely took over the STO n ICO trend.
As far I know I am not holding any STO tokens and I don't think I will in future.
It's a quick transition between ICO-STO and the new way that very popular now.
IEO's take over and become more popular than STO though the concept is just the same,
to introduced project that's in need of funding. Investors are now participating with
IEO's hoping to get the benefits after the sale period was over.