Service variues from crew to crew because every individual's demeanor and attitude is different, and probably changes every day. There's no way to get an answer to this question. I would venture to guess that you could collect "I was treated like a king by X" and "I received the worst service ever by X", where X can be any airline, just be searching the specific forums.

If you could do a global, massive survey, on a scale of 1-10, I bet the high to low would be about 4.5-5.5 with varience of about 4 points. Not enought to make any determination about a next flight.