2 Story homeowners of reddit, when you replaced your furnace/hvac did you upgrade anything so that you got better heating and cooler on the second floor?

Both my AC and Furnace are 20yo. I'm sure they will have to be replaced soon. My 2nd floor gets unbearably hot (we have to put window AC which is ridiculous since we have central AC). The basement will be 65 but the 2nd floor 79.

I'm wondering about dual zone, or even dual furnace/ac, or mini splits, kind of wondering what people did to solve this more permanently so I can plan some option when I do my replacement.