I felt the default GPT-5 responses were neutral. I checked and it hasn't yet emitted any emojis or exclamation marks, even though I used some in my replies. When I asked for a review of my question it focused on my query rather than me.

Will need to test longer contexts though - I've noticed Sonnet 4 becomes a bit less stoic and more friendly in some longer chats, but maybe it's just reflecting my casual language back at me.