I haven't made boudain or salami yet, but they're on my list.
For chorizo, my favorite is the "La India" brand seasoning. Just follow directions on the jug.
I've made all the rest and then some and I am a big fan of AC Legg's "Old Plantation" seasoning. I will often add to these seasonings depending on what I'm making. Will add extra garlic, peppercorns, japs & cheese to summer sausage. Will add extra minced garlic, paprika, crushed red pepper etc to my smoked pork sausages. Add to breakfast sausage...never added anything to the brats, not yet anyway. I am always tweaking a little here and there, but I use the Old Plantation directions as a place to start. When I first started making my own sausages I had planned on starting with my own recipes, but then I tried some of this stuff and changed my mind. Oh yeh, and I add 80/20 bacon ends and pieces unless the pig/pigs are really fat.