Singapore would probably be on top
Only as long as you disregard its political system: it happens to be a non-democracy. Economic development isn't everything, you know.
Development is an economic concept.
Regardless of the technical definition, as the starter of this thread, I meant socially/politically (i.e. democracy) and economically developed.
I think then you are trying to fit too many things into a single concept. If you want to ask which countries are most democratic, that's one thing (and is complicated enough by itself). But economic development is something else (also a complex mix of things that has often been critiqued as a narrow-minded construct). I think there have been too many counterexamples through history and even today to sustain the idea that the two go hand-in-hand.