Disclaimer: I'm a very light Twitter user. I'm almost surely missing out on features I never bothered to discover.
The main advantage G+ has in my eyes is its signal to noise ratio. It seems far better than Twitter's. Again, specifically in my professional world, quite a lot of relevant people post on G+. I guess they either don't post personal stuff or efficiently use Circles. Many, but definitely not all, are of course close to Google.
Some other advantages for me: the fact that you can read the whole story (not just sentence-per-sentence) and the -theoretical- ability to drag in non-professional relationships (yes, I like Circles).
I realize no one takes G+ serious anymore and that it's a graveyard for most. But it seems to work well for some (professionally). In a way it can make Twitter lose (one of) its edge(s): follow tech-people.
This isn't meant as a G+ promotion. I just wanted to make clear why Twitter might not be a good fit for some.