I use a tiny piece of freeware that has run on my Palm since about 1998 (yes, my requirements aren't as extensive as most users'). And if I didn't use that, I'd probably try GnuCash, which runs under Gnome on Linux but may have been ported to MacOS X by now.
That said, the people I've heard from who use MoneyDance on the Mac all seem to love it. I think there is a Mac version of Quicken, too. If GnuCash doesn't run on the Mac, I'd have to think hard about MoneyDance, because I use my Mac more than my Linux box.
But for me, it's just too handy having it all in my pocket.
Good luck,
Crikey