I have found Microsoft Word supplemented with MathType to be quite good.
MathType is the big brother of the equation editor that comes with Word.
Actually one of the most useful features of buying MathType to supplement the
equation editor is getting the manual which details the keyboard shortcuts for
typing math symbols, most all of which work with equation editor as well. For
example, ctrl-g-letter gives you the Greek letter corresponding to letter.
Ctrl-f gives you a fraction template. Ctrl-r a radical. I can type in equations
almost as fast as when I used LaTeX for my thesis. And the output is excellent.
Sometimes it doesn't get the spacing quite right automatically, but it is easy
to adjust spacing to be as you like.
Wolfram Research (of Mathematica fame) is giving away a beta copy of a
scientific word processor they call Publicon. It is to be the front end of
Mathematica. They also have done a pretty good job of thinking about efficient
typing and have come up with a similar scheme to MathType. (Ctrl_ gives
subscripts, for example.) Also, they give away a web browser plug-in so that
others can read Publicon documents on the web. However, I hesitate to get in
bed with Mathematica again as they have a history of prohibitively expensive
pricing.
And, of course, there are free version of LaTeX available that do perfect
documents with equations. They are not really WYSYWYG and it takes some
practice to incorporate figures. But it is free.