Mac Vector Image Tools
Adobe Illustrator.

You probably didn't want to hear this, because it's outrageously expensive, but it's the standard for a reason.  Inkscape is free and has a good number of features, but the user experience is pretty terrible.  Every other (cheaper) commercial offering I've used lacked even basic features that Illustrator had a decade ago.

I've tried using cheaper programs, but when they cost 1/10th what Illustrator does (or less), they invariably end up being 1/10th the program that Illustrator is, too.  I've not actually been able to complete a full image without exporting to SVG, and loading it into Inkscape to finish the job.

Maybe there's something out there I've missed (and I'd love to hear about it), but in my mind, there's two options: suck up having to deal with a lousy UI and use Inkscape, or suck up having to pay $600 and buy Illustrator.