Apart from a few games, Quicken is the last piece of Windows software that I just haven't been able to replace since switching to Mac OS X. The Mac version of Quicken is pretty much universally hated and is, from all accounts, a buggy piece of crap, and I have no desire to boot up a Windows VM in order to run the Windows version.
I tried a few other OS X finance apps and wasn't happy with most of them. MoneyWell was nice enough that I actually ended up buying a copy, but after a few weeks of use I discovered that it's just not as convenient as Quicken was (it also suffers from a few annoying bugs).
Somehow, while searching high and low for a Quicken replacement, I completely failed to discover Quicken Online until today. I was blown away. It doesn't have the full featureset of desktop Quicken, but it's got all the stuff I care about, wrapped in a gorgeous, responsive UI. They even officially support my new favorite browser, Safari, and there's an awesome iPhone interface for when I'm not near a computer. Within five minutes of signing up I had imported all my accounts and was ready to go.
If you haven't taken a look at Quicken Online yet, I recommend checking it out.