@EricIronside wrote a great article on the topic of choices vs. filters:
https://community.esri.com/t5/arcgis-geoevent-server-blog/geoevent-10-9-introducing-choice-elements/...
From that article:
"A choice element with one when clause and the optional otherwise route disabled is functionally equivalent to a filter element."
In other words, if you want to process both TRUE and FALSE, use a choice, but if you want to process only TRUE or only FALSE, you can use a filter or a choice.
I would use a filter in the latter case because a choice restricts what kind of input it will take. From Eric's article:
"Each choice element must have at least one parent element and that parent element must be either an Input element, a filter element, or a Processor element."
I have encountered situations where I had to add a No Operation processor to get a choice to work. It was worth it because a choice is better than multiple filters, but it would be easier to use a filter if you needed to process only the TRUE case or only the FALSE case.