To paraphrase Mama June, I sweat like a prostitute in a church

so I struggle to find suitable deodorants. Devlyn's suggestion of a fragrance-free anti-perspirant is a great idea, but I find that men's deodorants tend to be more effective than women's deodorants, so if you can find a men's version (which is difficult) that might be preferable.
I also have sensitive skin which tends to become sensitised to deodorants, which means that if I spray myself with one of the deodorants to which I'm intolerant, I start sweating profusely as my body tries to wash it off my skin.

So I keep a selection of four different deodorants, and I cycle them every few weeks so my body doesn't have time to get sensitised to them.
Another good suggestion is to try roll-on deodorants. There are some with all-natural ingredients; some with extra-strong anti-perspirant action; some that don't leave white marks on your clothes; and some that are unscented. They're worth taking a look.
Oh, and I clean myself several times a day to get rid of the sweat. If it gets really bad during the day, I keep a pack of unfragranced baby wipes (the kind you use when cleaning their behinds) so that I can wipe my armpits and reapply fresh deodorant. I don't stop sweating until my final wash around 8pm.
Aand finally... I found that adding the recommended dose of disinfectant to my bath water (the type you'd use to sanitise cuts) helps to stop me from sweating so badly, because it kills some of the bacteria on the skin. I don't recommend doing this all the time, but it can be very helpful on those days when you're super-sweaty.