1. LHR T4: best breakfast spread and usually very quiet (especially upstairs)
2. AMS KLM Crown, non-schengen: spacious, quiet considering the size, decent food (make your own ham sandwich ), plugins at almost every seat - and the chairs are comfy. I've had nothing but great service from the ticket agents who are stationed in the lounge.
3. ICN KE: huge, decent food, easy to find a private area
4. NRT: mainly for the food; comfortable, but they can get very crowded at times (doesn't handle crowds as well as the others, otherwise it would be higher on my list)