Delphi 3.0 (it went downhill after that). You could slap together a GUI quickly in the form editor, wire it up to your code (i.e. fill out the auto-generated ev

Delphi 3.0 (it went downhill after that). You could slap together a GUI quickly in the form editor, wire it up to your code (i.e. fill out the auto-generated event handlers) and compile in seconds (on a 1990s PC!). There was a large selection of add-on GUI widgets and non-visual components, free and commercial, you could make your own and you could even modify the core Visual Component Library (the source was included). If you needed to talk to other applications via COM, or directly to the OS, or load C/C++ libraries, it was easy. And you could do all that in one integrated IDE, instead of having to learn and orchestrate a jumbled mess of different tools. It also didn't hurt that by targeting Windows only back then, you had something like 90% of the potential market covered. It was bliss while it lasted.