>>11896640
>Which tool do you personally suggest?
Ultimate Doom Builder for making levels.
Slade for handling the files inside a .wad

Then past that, it's what kind of programs you like working with, for making graphics you can use AseSprite, Gimp, or Photoshop, hell, you can even use MS-Paint, which some people were outright doing way back in the 90s sometimes (with varying results).
Some people will pre-render stuff in 3D, which is how the new monsters in Rekkr were done, or you can even do it like iD Software themselves did, and digitize real models and props, which a few people occasionally do for projects still.

For sound, you can use Audacity.