Q-tec is the one most folks get.
If you ever order anything from 4wd, you'll get their catalog as well though it's not as nicely done as q-tec.
Does JC Whitney make a catalog? I feel like I've heard theirs is good.
The reality is IMO though that q-tec is really all you want for catalogs. Q-tec is a good, general source for decent products and the catalog is nicely done.
Beyond what q-tec offers, I find myself looking to smaller manufacturers that don't really offer catalogs.
Put another way, you always want a good generalized source, but you don't really need more than one. And for specialized stuff, you look to specialized sources.
Not sure if that makes sense . . .