If you run straight Mac OS X (no Boot Camp), there is currently only one choice: BeerAlchemy. BeerSmith is developing a Mac version but it wasn't out as of a few days ago.
I run BeerAlchemy ($30 registration) and like it (though I can't compare it to others). It has a sync feature so that I can have my recipes, batches, ingredient lists, and calculators on my iPhone (I don't know if they have a version that runs on Android OS). On the down side, BA doesn't load xml recipe files (it claims it does but every xml file I've attempted failed). It does import .rec recipes, with some tweaking.
For smart phones, Sparge Pal is free and has some nice features.
Good luck with the search.