Can I ask career advice? Long story short I'm acting in a senior role at work ( in my current department).

Pros: I'm loving the opportunity and the fact that I know the content; it has given me an opportunity to invest in myself with personal growth ( only a slight pay rise on my normal role).
There is a possibility that I can secure this role permanently which means a potential pay rise of 12k guaranteed over next 5 years but this is only a slight possibility.
The area is expanding and will be new and fresh.
Both my boss and his boss have pulled me aside and said they want me to stay in the role I'm doing.

Cons: No career growth in this department from where I am. Potential toxic people return. Potential to go back to my normal role under these toxic people.

Option 2 is new department with new content.

Pro : career growth, It's 13k more than what I'm earning in the senior role. Opportunity to make my mark. It's something new so great learning options

Con: less time to focus on personal growth, possibility will not guarantee senior wage and drop 16k back to my normal role once this temp role is over. Still be under the toxic people if they come back

I'll add we want to ttc for #3 at the end of the year.

I'm tempted by the extra $$ short term but know the current role will provide personal growth.

What would you do?