I've had type 1 diabetes for over 30 years. over the long-haul, which is worse: the occasional high sugar (over 200) or the occasional low (under 60)?

Depends: Depends on age and comorbid conditions. But, neither is preferred. Likely less problems with the high than the low.

Some thoughts: Chronic too high= damages nerve endings eventually, causes changes in your retinal tissue, triggers cataract formation, damages kidney cells, and so on. The brain & heart requires a basic supply of sugar for every moment of function & cannot use other molecules for this energy. Too low risks these functions and a single episode may kill you. Mild episodes either way have little effect.