I spent two Weeks with a doepfer modular, an early pi coscope (borrowed from school) and groundwork on repeat when I wrote a paper on sound synthesis for a shorter electronic education. That was five years ago and the scope worked flawlessly. I just remember it like fragments from a dream, probably the happiest time in my life... :-)
The software didn't have a lot of functions which probably has evolved since but the simplistic take on it made it extremely easy to use.
It's the first scope I'd consider...