My answer to people asking about "What's the best LaTeX environment on the Mac" has become sort of a personal FAQ. Naturally, it depends to some extent what you used on the PC side before.
Nowadays, I generally point people to the easy-install
MacTeX package, which does a whole TeXLive-based install and adds the standard, basic GUI front-end clients, like TeXShop and BibDesk. Most people get on fine with those.
Nowadays, looks like I do
most of my work in my text editor of choice (
TextMate), and run the (PDF-centric workflow) job from the command line (alternatively triggered with a keystroke in TextMate), and open in Preview, which now automatically refreshes the document with each new LaTeX run.
If you haven't done so, do yourself a favour and switch to a PDF-centric workflow for TeX. This may be a more dramatic change than moving your files over to Mac, but I think it will reap the greatest rewards. The PDFTeX world is now much more capable than the classic PostScript workflow, and it integrates beautifully with Mac OS X. If you were to spend money on one application to support LaTeX on Mac, I would suggest looking at the exemplary
OmniGraffle for diagramming. Simple to use, makes very sophisticated things possible, and gives gorgeous results.
And, I wouldn't be true to myself if I didn't plump for the
ConTeXt macro package as an alternative to LaTeX. If you want to write up a structured document, but it's not for a conference proceedings or journal, I would say that it's more worth putting the time
in to learn the basics of ConTeXt than, say, the Memoir class in LaTeX. ConTeXt's way of separating form from content feels much cleaner than LaTeX, and I feel like the learning curve for ConTeXt has a fairly constant and gentle slope, rather than a hockey-stick-like bend for when you want to customise a Class file.
I could go on for hours more, but that's enough for the basics.