ublock is great software (it didn't exist when we started work on PB!) and so there are only a few things PB will catch that it doesn't. But there are some. For instance, PB will replace widgets such as Tweet and Facebook like buttons with locally hosted, non-tracking variants. And PB may catch new trackers faster than ublock because it uses algorithmic detection rather than requiring a blocklist.

You can use Privacy Badger on sites that you want to support with ad views (as long as those adds don't track you).

A good example of this is many of the webcomics I read. Many of the adds on those sites are for other webcomics, I've found a couple of good new webcomics that way.

Much better to simply buy their merchandise instead.

Yes. I use both ublock origin and privacy badger and for the majority of sites both plugins detect and block stuff.