What do most people use/prefer?
Almost every web design/developer job I see requires experience with Dreamweaver. I haven't seen one job ad that mentions Expression.
I tried Dreamweaver, briefly, and couldn't really understand what it could do that Expression can't.
Expression Web is a Microsoft product and I can tell you are a Microsoft .NET architect and developer Expression Web is really only better than Dreamweaver in one area, ASP.NET development.
And even then, I would choose to use Visual Studio without even thinking about it over Expression Web. So, unless you are doing .NET development I would stick to Dreamweaver. If you decide to do .NET stuff, look at Visual Studio.
I would pass on Expression suite, and that's from a MS guy.
Btw, to answer your question, personally...
1) I use Dreamweaver/Notepad for anything non asp.net
2) I use Visual Studio 2008 for asp.net development