From my experience KLM have given me the most fun in terms of enjoyment. Their attendants have always been polite and happy to have a chat when I have flown them, plus I've always had good legroom and whole rows to myself on long haul flights which increases my enjoyment of the flight dramatically!
In terms of the actual flying then its a close tie between Iberia and Air Southwest. IB
really know how to fly their Mad Dogs to the edge which is great, but bouncing through the cloudes on the latter in a Dash 8 can be great fun too..not to mention to rough landings we get down here during the winter
...love is just a camouflage for what resembles rage again...