Everything depends on what we are really looking for.
If we are on mainstream side, we can find what we want almost everywhere.
If we want more rare content, we need to focus on certain
trackers that are more or less unique, so no back ups for those
In general, it's good to be members of many
trackers, so we can regularly use some of them and occasionally can search missing content on the others
It's not good though to be members of
too many trackers, because it's practically useless as well as we just can't handle them.
Last but not least, because we certainly don't want to spend most of our everyday lives in front of a computer monitor