For editing text Vi and Emacs are preferred by quite a few hackers.
However for editing Scheme, DrScheme is the best choice.
Not because it is "graphical", but simply because it was designed with one purpose only: writing Scheme code.
It has all the standard stuff (such as: to show the documentation on an identifier just press F1), but
it also contain the Scheme specific stuff, that you
won't notice until you try some advanced Scheming.
Among the most impressive features is how precise the error messages are reported. This goes for both standard errors, but not the least when macros are involved. If you compare the error reports you get from a few errorneous macros in DrScheme and in a standard Scheme implementation, you'll see that you can save a lot of time if you use DrScheme.
And while at, don't forget try the macro stepper...
i like drscheme in general. there is one problem with it that made it simply unusable by me. when you hit run in drscheme to reevaluate your definitions, it obliterates my entire history in the REPL. i need to have that stuff around to retry expressions.