I have very strong opinion on this one!
SFO-HKG flights are ALWAYS great for me! I love the crews. They are happy, helpful, and warm. Always on top of things.
SFO-FRA flights are ALWAYS terrible for me! I hate the crews! They are surly, unhelpful, unhappy, and cold as dead fish. I can go 2 hours without seeing an FA, all the time with my glass empty.
IMHO, is is much more about the crew than upper vs lower deck.