uBlock is a static blocker, afaik. If a URI doesn't appear on a list currently loaded, it's not blocked. This can allow unknown and dynamic-URI trackers to follow you across many sites. Privacy Badger looks for resources that appear across several domains that behave like trackers. If it sees something that looks like a tracker more than a few times, it's blocked. I use uBlock to block the majority of ads and trackers, and I use Privacy Badger to defeat the remaining trackers and other tech aimed specifically at users with ad blockers.