TDK - New heights in HiFi...

Early 1970s SD90 - a forgotten tape, by all accounts.  There was an Optimal Dynamic as well, I believe...

Acoustic-Dynamic from around 1976 - allegedly superior to the Basf LH Super.  ADs are still manufactured today.  I think.

The most popular cassette of the '70s?  The TDK D - this example dates from 1978 - note the slight label and cover redesign.  A Which? test in 1977 put it in top place...