I don't think respectively works here.
(in listing a number of items or attributes that refer to another list) separately in the order given:
he gave Janet and John a cake and a chocolate respectively.
This means that Janet got a cake and John got a chocolate.
There is also this definition
in precisely the order given; sequentially.
But I don't think it would not imply which order you intend, high to low or low to high. So, I would not use respectively in this case. I would instead consider
- After these, X, Y and Z followed, from most to least preferred.
- After these, X,Y, and Z were preferred, in decreasing order.
- After these, X,Y, and Z were preferred, where X was most preferred, and Z was least preferred.
This is assuming that X was most preferred, and Z was least preferred.