I am curious which is worse in terms of contribution to modern chronic metabolic disease.

In the case of ultra-processed/refined oils though, there is an argument to be made that these are novel foods that humans never ate until very recently. There aren't any old people who have been eating them their whole lives in the quantities we do now. This is probably true for industrially refined sugar too, but sugar is a more complex story since people have been concentrating plant sugars for a lot longer than they've been industrially refining oil for food.

I'm not defending sugar though to be clear - I strictly avoid it and even avoid fruit juice and such. I know empirically for myself I feel terrible if I eat very much sugar. I also feel terrible if I eat much refined oil and I strictly avoid that too.