The OS X version of Quicken is simply too buggy to use. Accounting data is one kind of data you don't want to get corrupted, but Quicken corrupts it. See complaints on VersionTracker for details. This isn't a new thing with Quicken; it's been true for years. It's quite remarkable that they don't fix their data store.
When my accounting data became corrupted a year or so ago (which happened without a crash or other knowable cause), I gave up. I looked around for something else, and found MoneyDance. MoneyDance isn't the only accounting program that's well-reviewed on VersionTracker, but it's the only one I've seen that runs on OS X, Windows, and Linux. The fact that it's written in Java undoubtedly helps there.
At this point, I'm not aware of anything I care about that Quicken has and MoneyDance doesn't. Plus, online banking works on OS X for MoneyDance with some banks that don't support it for Quicken.
MoneyDance has been improving at a relatively rapid pace. Another important factor, to me, is the fact that it is in a unique niche due too being the only easy-to-install-and-use accounting program (that I know of) that works on all three major OS platforms. I think that gives it a competitive edge that may increase its chances of being around in 5 years, compared to its OS X-only cousins. I don't want to have to switch accounting programs again for a very long time.
Oh, and one last thing -- you can write extensions in my language of choice, Python, that access MoneyDance data. I haven't done it yet, but I'm glad to know it can be done. I assume that facility uses jython, a variant of Python that runs in a JVM.
I have no association with the product or company at all, other than being a happy user. If you use OS X or Linux and are looking for a reliable and easy-to-use accounting program, I heartily recommend MoneyDance.