GWBasic was good resource to get into programming world during my teenage. Now I want to teach coding to my 10 years old son. Will you still recommend GWBASIC/Quick basic or Python or other languages for kids?
1. Computers are so much more advanced now, that the obvious gap between beginner and commercial software is vast. This can be discouraging. When I learned BASIC, I could write programs that didn't look any more crappy than typical commercial software, even if there was a performance gap.
2. There's more magic involved today, meaning that when you run into an obstacle, you wave a wand and a library or stackoverflow post magically appears. To do something in the old BASIC, you had to figure out a way to compose it out of the 13 keywords that you had already learned. So you were forced to think about algorithms, right off the bat.
3. You were closer to the hardware, which was more exciting if you were interested in things. I could kinda explain what the computer was actually doing. I loved math as a kid, but I also loved electronics. The day that I programmed a thing to do something (maybe just a blinking LED) was like the rapture for me.
What's closest to the old experience for me is not a language, but a thing: A microcontroller board. Out of the box, it has no GUI, so no expectations for what "cool" software looks like. And you can make it do things that have an immediate sensory effect. You can now put CircuitPython on a Teensy 4.0 board, and sidestep having to learn C, at least for a while. And your son can really own the thing that he's programming.
As a minor suggestion, you can also get closer to the computer and to programming by making more use of the command terminal when showing your son how to do things.
A final word, don't be heartbroken if it doesn't click. It might not. This is also something parents are told when their kids start music lessons.
The closest thing I'm aware of today, that are actually useful, are the 8 bit PIC chips.
Also, I can't help thinking of how it can be counterproductive to try to push someone in a certain direction.
A lot of times showing what you value and want for yourself tends to have more influence than what you try to get others to value.
Python itself is great because it has all the right batteries included. It's easy to get started - you don't need to explain "import" or functions to write a basic hello world type app with console input and output. Then you can gradually build it up from there, introducing turtle graphics, databases (SQLite), and finally GUI (Tk) - all of which are present in the standard library.
And Thonny, well - it's self-explanatory once you see it: https://www.youtube.com/watch?v=nwIgxrXP-X4
It also helps they use known franchises like minecraft or angry birds =)