I use an alum stick that was purchased from a natural pharmacy. It is odorless and doesn't cause irritation - problem I have with any main brand product. As for fragrance, I let my body soap, after shave, and cologne handle that.
I agree on letting other products do the fragrance work, so I go for an unscented anti-persp/deodorant. Am finding that Mitchum gel works quite well. Its not "natural" though. But then, "naturally" we are supposed to stink
Unless its a problem with irritation, I personally don't see anything wrong with the ingredients used in most deodorant/anti-perspirants. I've looked at the research papers, and the jury is still out about whether the aluminum based products pose a cancer risk. When you think about it though, in the big picture, what are we exposed to every day that doesn't pose the slightest increased risk of cancer? Pretty much everything has the potential to do it.
My decision is to stay away from the things that GREATLY increase the risk of cancer, like smoking and live the rest of my life rather than fear everything.
That said, I've heard that Whole Foods markets have a good natural crystal deodorant. Try checking that out.
This does work well for me. I usually carry a travel pack of Antibacterial Wet Ones in my pack when I'm hiking or know I'll be sweating. I have not had any irritation ever since I stopped using mainstream deodorant.