The key ingredient in Marsala Chicken is Marsala Wine. While there two kinds -sweet Marsala and dry Marsala, either can be used. I personally prefer the taste of dry Marsala, which keep in mind, is still sweet, just a little less sweet. If sweet Marsala is what you have, just use it. Sweet Marsala works fine too. Regular red wine, will not work the same here.
VEGETARIAN OPTION: In our catering business, for vegetarians, we would substitute tofu “filets” dredged in the flour mixture, pan-seared the same way. Instead of chicken broth substitute veggie broth. A decadent vegetarian dinner!