Another vote for fish. I would say another benefit is that it has a reasonably great out of the box experience with little customization needed to get a lot of its benefits, eg awesome autocomplete.

The downsides have been mentioned, namely the lack of compatibility with shell scripts not written for it. In the same vein, until somewhat recently, operators like && did not work for it.

It’s still my daily shell, and I really only use something like bash when having to remote into a production server.