I like using a third party alternative since it gives me the option to use it outside the google ecosystem. I use Firefox and Chrome regularly so the seamless syncing without depending on any particular browser is important for me.

The other feature I like in dedicated password managers is that they tend to have a lot more options about what kind of password/passphrase you can generate. Some other features that i regularly use is storing non password content like software licenses, sharing certain passwords with my spouse, etc.