How do you know that a journal is a predatory journal: is it due to unsolicited emails requesting for manuscripts or the speed at which the manuscripts are published or what?
Journals that send unsolicited automated emails are generally to be avoided. Its less that they are all predatory and more that they lack the reputation to attract submissions. Overall it is probably less important than ensuring a journal allows you to share electronic versions of the article (as this is the main way in which paper's receive exposure today).