I really only use three grooming tools (besides a hoofpick) and I still take longer to groom than most of my friends! These are my main tools:
Metal curry- for mud and shedding
Rubber curry- for mud and massages
Medium/stiff brush- when they are basically clean and just need dusting off
I own a couple of soft brushes but don't use them much. I have one soft brush I use on the foal because I figure his skin is more sensitive than a big horse. But otherwise, I basically get by on those three tools. Heck, if I could only own one grooming tool (besides a hoofpick) it would be a metal curry. I can pretty well get the whole horse the way I want with the metal curry!
Tip for Smrobs, and other western riders- use a single layer wool blanket under your main saddle pad to collect all the dirt and sweat. I used to HATE washing the big, thick pads. Now I never have to! I just wash the wool blanket (when it is still sweaty from being on the horse it rinses pretty easily) and viola, no big pads to wash. It's much easier washing a single layer wool blanket (like Mayatex) than the stiff pads. Since I've started doing that, I've never looked back.