Here's what I'm planning to do for the ducting.
I live in a two-floor house (total area 90 sqm), ground floor is another property, on the first floor I have the entrance, an open space with the kitchen and a slightly separate living room, a bathroom and the stairs that lead to the attic. There I have a small corridor, another bathroom, a studio and two bedrooms.
Behind all this there is a small place (25 sqm) used as a closet. I will install the HRV there as I can easily reach every room using short distance ducts (max is 5 mt long). I will plug the main inlet and outlet to the outside via the roof right above the machine (the drawing is quite schematic, in and out ducts will be much more distant from each other).
On the first floor I will have fresh air in at the living room while taken the stale air from the kitchen area and the bathroom.
On the attic I'll plug the fresh air in the bedrooms and take it back from the bathroom and the stairs arrival (in that way I'll get some of the kitchen odors that inevitably go upstairs + max hot inside air).
I think it's quite balanced like that. The only problem is that I'll have to make three 120mm diameter holes to the attic towards the first floor, that's 45 cm thick!
