A brominator will /should be able to deliver proper amounts of chlorine to sanitize your water. Dichlor and Bromine are both considered very aggresive sanitizers.
Ozone, is a more passive system. Many folks claim that an ozinator by itself cannot sanitize the water effectivly. It's a suplimental unit to a more rigorous saniiation program. The people who have an ozone system typically report good results, but there are some who feel it's doens't make a difference.
Then on the other side of the coin, There are a few kooks...um...er... folks who claim that there are tubs that use only an ozone system without any other sanitizzer and have no problems for years. (or so they claim).
Bottom line is (IMHO) Aothough there is some dispute over , most folks who have one with a 24 hr circ pump report improved water quality.