I have been using mainly four data plotting software. CA-Disspla and CA-Tellagraf were for a long time available at Helsinki University of Technology. When their licences were not renewed I begun to use both Dislin and GnuPlot.
A commercial high-level user interface that uses Disspla-subroutines. I liked this one.
DISLIN is free for Linux, but no source code is given. DISLIN resembles Disspla, but DISLIN is much easier to use. I recommend to use DISLIN instead of Disspla.
GnuPlot is an independent free data plotting software. It is rather easy to use.