I feel your pain. I’m in the midst of a big review of rain shells for the parent magazine of this site, and it does indeed get confusing with all the different fabric names out there.
But it can be simplified a bit. Basically, there are two kinds of waterproof-breathable materials out there: Membranes, and coated fabrics. Membranes are themselves waterproof (Gore-Tex is a membrane), without any modification. Coated fabrics are just garden-variety fabrics of one sort or another, with a coating (usually polyurethane-based) that has a microscopic structure which allows water vapor generated by the wearer to escape, while keeping rain water out. One confusing thing is that coated fabrics sometimes are used like a membrane – that is, sandwiched between two other fabric layers the way Gore-Tex is in three-ply construction.
You also can break things down this way: As a general rule, all the Xalt’s and H2NO’s and Triplepoints of the world do a pretty good job, but don’t breathe quite as well as Gore-Tex. On the other hand, they’re cheaper, breathe pretty well, and in some instances – particularly if the face fabric on the outside of the garment is very wet – may perform better. About all you can go on are generalities and personal impressions. There simply is not a single standard – at least, one that everyone agrees on – that measures the waterproof-breathable qualities of the many fabrics out there.
That said, a few recommendations: Kokatat’s Lite Wave Drytop ($314) is a high-quality Gore-Tex piece that you just won’t be sorry you got, although it is a bit pricey. Rapidstyle’s Cataract top ($185) uses a coated fabric for a jacket that performs well at a considerably lower price than a Gore-Tex piece. At an in-between price, Stohlquist makes a basic top called the Contour that uses Gore-Tex and costs just $200.