I use Dreamweaver primarily because I had been using MS Frontpage on PCs before I got a MacBook back in December.
There is no other web management software for the Mac that compares to Frontpage. At least, not that I've found.
I tried iWeb, NVU, and Rapidweaver. None have the all-in-one flexibility that Dreamweaver has. Since most of the stuff I do at this level is maintanence of existing sites, this was important.
At first, I was intimidated by Dreamweaver's reputation for being a steep learning curve and hard to master. I have since learned that it seems to have more robust features, but isn't that different from Frontpage for interfacing and making changes/updates. It just takes some getting used to.
In reality, I've found it has some features I either never used in FP or FP doesn't have, to where I have abandoned Frontpage altogether and will continue with Dreamweaver, even on a PC platform.
Hope that helps.