Mac options for dive computers:
1) Suunto, using DiveLog. 100% Native Mac, although not manufacturer endorsed, if that matters.
2) Uwatec, using jTrak and the Uwatec (or compatible) IR interface. 100% native Mac, although not as fully-featured as the Windows SmartTrak software. Manufacturer-endorsed, but not especially well-maintained, IMO.
3) Oceanic, if you don't mind waiting for Oceanic to get off their duff and release some Mac software, and using Parallels/VMware in the meantime.
4) Sensus Ultra recorder, plus any computer you want. Sensus has 100% OSX native software.
I don't see much point to arguing about algorithms in a thread about Mac options for dive computers... that discussion should have it's own thread.
I'll agree that I'm not a fan of Suunto's overly-conservative algorithm, however. I prefer Uwatec, with Oceanic as a close second. I'd generally recommend Oceanic to a newer diver, since they're more user-friendly out of the box, and Uwatec to a more advanced diver.
I have both Macs and PCs, and while I've dabbled with jTrak, I like SmartTrak much better. If I was Mac-only, I'd probably use SmartTrak under Parallels. I don't mind Parallels in the slightest, especially considering how rarely (relatively) the software actually gets used. If you're diving more than twice per week, maybe it would be annoying? But even at twice per week, it just doesn't seem like a hardship to fire it up. I then import my logs to
DivingLog's excellent software, and load it into companion software on my iPhone for ease of reference. (Before, I would load the Uwatec IR directly into AquaDiveLog on my Treo, which then imported automatically into SmartTrak.)