I have experienced quite a few of these - Singapore Suites, Cathay First Class, Qantas Suites, British Airways, Malaysia all on A380 with the exception of Cathay.
Singapore Suites deserves to be the top - the comfort, food/wine and service are all much better than the rest.
Have to say that the A380 service on BA is the worst A380 service I have experienced - the food is poor, the seating design is disappointing (it is basically the old first seat with extra width. The toilets in First on the A380 are smaller than the toilets in Business and are nowhere near as nice as the toilets in Singapore or Emirates. One would have thought that BA would have used the space on the A380 to come up with a ground breaking seat and cabin design for First but sadly they did not.