Level editors for Quake era games such as Worldcraft and QERadiant originally got me interested in game development and even to this day, as a programmer, I find Blender and others a lot less fun than these original tools were. ProBuilder and UE4 brushes got close but I don't find it generic enough to use the same tool for the number of different game engines I typically use.
So as a side project, I decided to considerably hack at the GtkRadiant level editor source code and turn it into a more generic 3D content creation tool. As just one example, rather than read Quake 3 data files, instead it reads from a standard filesystem (as you would expect a normal 3D modeller to do). I have also added a "standard" .obj (wavefront) exporter making it easy to read directly into other modelling tools as part of your build pipeline.
Finally I have replaced the older Q3 lightmap baking stuff (the q3map2 compiler) with my own called "Raptor Bakery" (Or you can use Blender's, Mayas, etc anyway because it exports to .obj).
Basically you can easily port your Quake maps to other engines.
So if you are interested, please check it out. It is free and thought others might enjoy it!