GFA Basic on the Atari ST was my true entry into programming, and I went through many other languages before I found one that felt as modern and productive.
I used both an Atari 8-bit and ST and wasn't aware of GFA Basic (or Turbo-Basic XL found on Wiki page). They would have been cool to have. On the ST I was using Megamax C compiler on one diskette and programs on another.
Yes. Great language, relatively fast, surprisingly modern (at the time - came out in 1986), lots of fun.
GFA was fantastic. I used it for various telecommunications programs back in the day. The only thing I really wanted as an addition was data structures.
It is still around, in a maintained 32-bit Windows version.