Whilst a little lower on the food chain. Is the Alfa Giulia Quadrifoglio an option? Or even just the normal petrol variant.
Still something a little different from "another" BMW, but a step up in general build quality and considerably cheaper.
Panamera?
I think changing because you just want 'a change' is usually something that will result in failure once you get used to what you get next and the excitement of something new fades revealing only the differences between the previous and new car. For change to work, it needs to be either something completely different or something that is quite obviously superior. The reality here is that there isn't much change - you'd be changing an automatic diesel rear wheel drive saloon car for an automatic diesel rear wheel drive saloon car. Only one that isn't built as nicely, isn't as nice inside, lacks the technical features, etc. Eventually, you'll come to regret the change.
So, either:
a) Change for something genuinely different - a sports coupe perhaps
b) Change for something genuinely better - perhaps a W222 S Class or a G11 7 Series
The Maserati name is iconic amongst car enthusiasts but none will be thinking of the automatic diesel saloon when they think about Maserati.
I always thought car enthusiasts made fun of Ghibli owners, tongue in cheek?. Well, ghibli used as a derogatory term anyway.
"An individual who outwardly gives the impression of lux and wealth but who is actually cheap and hollow at heart.
This term is an allusion to the Maserati Ghibli, an automobile that seems high class because of its branding but actually has a very cheap quality interior for its price level.
Example use: Simon wears very expensive clothing to cover up his lack of likeable personality. What a Ghibli"