I would decide what type of element works for you then find the company with the best version of that element.
chemical (which you already use)
strain (filter style which you are looking at)
U.V. light (like the sun)
The most popular is the filter style. those have fiberglass, ceramic, hollow fiber, and carbon mediums. For preparedness sake I would use something with a backup.
Ceramic elements are easier to clean and give the filter longer life. They get about double the output of a fiberglass. they are similar in speed to the fiberglass maybe a hair slower. They can crack if dropped a far distance. even a few feet if out of the filter housing.
Fiberglass elements are faster, they get less output and they are harder to clean. they are more resilient and more dummy proof.
hollow fiber is by far the fastest. it is similar in output life to fiber glass. also generally the lightest due to more surface area per weight. these can be purifiers and not just filters. kidney dialysis uses these.
chemical you know about.
U.V. light kills everything these are purifiers not filters like the rest. they deactivate the DNA in the bad stuff so it can't reproduce so it just passes through. These require batteries is the down fall and only do a little at a time. Many cities use U.V. light.
Your back up can always be boiling it.