In 1997, my favorite 3D tool was a Quake map editor called Worldcraft. I ordered a full version, and a CD arrived in mail a month later. (I think it took some extra time because Ben Morris, the creator, had recently sold it to Valve; you can see the copyright info on the cover.)
At Valve, Worldcraft would, later, get turned into Hammer, which would be the standard tool for working with Source engine games.
Previously, I would not have expected to prefer using Worldcraft to using real 3D tools like Autodesk’s 3DStudio. After all, in 3DStudio I could create highly complex models, realistic renders, and animations. But I hadn’t yet learned the ways that the experience of creating is as much a motivator for me as is the fidelity of the creations. While I could make interesting models and scenes in 3DStudio, I could build interactive worlds with Worldcraft. And while either tool could be used to work iteratively, each iteration of an interactive system can be deeply pleasurable, even while incomplete. I was hooked.