The 2 best arguments to use are financial and speed to market. If the team is already familiar with Angular than you have both arguments you can make. If the team is already using React you have an uphill battle that honestly may be the wrong choice.
There are technical and financial reasons for most frameworks. Frankly, I am not a fan of either framework you are choosing between and if I was choosing something new now I would probably heavily investigate Vue versus either of those.
I am also not a fan of SPA's or heavy client side rendering either. Personally, I prefer to see more server side rendering with additive client side functionality. There are exceptions of course.
No matter what, I'd still be weighing all the options based on the team makeup and product requirements, as picking any framework(s) or design before you know the requirements is usually not a good idea.
