In a recent blog post, Jason Miller argued that one of the things we need to the gravity of is the goetia. His point is that working with goetia has defined how people work with spirits and that it can become an obstacle to discovering your magical path. I agree with him, but in thinking about it, I realized that one of the reasons I like to work with the goetia and other established spirits sometimes is that they may not be the most powerful entities out there, but they are convenient to work with, in the sense that people do know about them and have some awareness of what expectations are involved.
But with that said, I think its important to expand your horizons. I do work with Bune, but I also work with Dragon. I have worked with Purson, but I've also worked with other time and space related entities. I've worked with the classic elemental spirits, and I've also chosen to explore the possibility of working with other elements.
There's value in going with what's tried and true, but there is something to be said for leaving the convenient behind and seeing what other spirits are out there. Thus lately I've been working with the planets, both in terms of contacting the archangels, but also working with the spirits of the planets in and of themselves. But you could just as easily work with Franz Bardon's lists of spirits, or with spirits from other grimoires.
At the same time having hopped on the Bune band wagon myself, I can say that choosing to work with him has been useful because he's getting so much notice. If everyone's working with him, there's probably a reason for that.