I thought KL was nice, above average but not in the same league as Changi and Hamad
Recently went to both Changi and Dubai airports on the way home from Australia, gotta say that Although both are quality Dubai wins for me: IT HAS BLOODY WATERFALLS
I will have to admit I may be a bit biased but Düsseldorf International Airport (Germany) is very modern, attractive and efficient! Architecturally speaking I love the look of Beijing Capital (as viewed from above). Zürich perhaps has the best gimmick in the world (the shuttle trains between the hub and spokes have cow bell and swiss alpine noises like horns whilst you ride). Everyone always laughs and smiles and the day is definitely brighter after transferring there- fantastic marketing trick!
Koh Samui has a beautiful airport- feels like you're in a fancy resort!
There are a lot of rich people posting in this thread. I've never been to Dubai, nor do I want to either. Zurich is the nicest European airport I've been to. Its clean, spacious, and efficient unlike all the British airports, which are confusing, messy and expensive. Having said that I found Vienna's airport very interesting, but it was under construction when I visited...
Clearly Singapore Changi Airport for me - no competition. I really miss my Singapore days. The epitome of efficiency, organization, and "feel".
Zurich Flughafen is decent too.