I lived in KL, SIN and BKK and frequently transited through HKG. Just recently spent some time in the new lounge @ HKIA, the new Pier First Class lounge - amazing, especially the food (although I admit, the lounge experience can be quite 'superficial' in many ways).
The lounges at KLIA have seen their better days I am told (they are generally OK for me, and of course beat any UA Club). As for SIN lounges, depends if you are on SQ or *A flight, as not all *A Golds have access to the SQ Business lounge (which is nicer and has great food).
As for the US, I am quite OK with the AA Flagship Lounge @ JFK (the first class lounge, not the business class one - huge difference), and in the UK, the BA Terraces First @ LHR is fine as well (nice views and a separate terrace-like seating area).
The one lounge that surprised me positively, mostly because I did not read about it ahead of time and did not know what to expect, was the Qantas First Class Lounge @ SYD - I wanted to stay there for ever : excellent food, great service, beautiful views, etc.
As for our adopted continent, the *A Gold lounge @ EZE is nice aesthetically, but lacks the food and the service you would get in Asia. I accept that, and enjoy what I can. Same for the Iberia/Lan/AA lounge @ EZE. The old *A Gold @ GRU was horrible (and I remember the old UA lounge @ EZEZ equally bad), but I heard it got renovated. The new Avianca Lounge in BOG is quite an improvement, but again, the lack of good food and service takes away from the otherwise good hard product.
I´ve been through Heathrow and airports in many countries. US are the worst I´ve encountered because a % of the immigration officials are sadistic (I´m not referring to the people who scan passengers and luggage). I´m referring to the characters who´ve illegally sent Canadians to a third country against their will,, put people in jail for asking questions (check YouTube), ec. A passenger in transit to a third country, sometimes has to get his luggage, line up to show it to a customs guard, then line up for immigration (seriously, I was in a line up was about a kilometer long in Miami !). I also find there´s a lot of problems with flight delays in the US. As my US friend (a
high ranking military officer) says: he´ll fly again, when the (US) airlines treat him better than the turkeys being trucked down the road to the slaughter house.
They are hell if you get flagged I got flagged once I think it was because I changed flights 3 days before. Nothing like being treated like an animal by the TSA monsters while they get rocks off treating you like well you know.