I don't think it is fair to count KTM, DEL, etc. in this discussion. Those are not even "real" lounges to begin with. And these cities are hardly major hubs of Star Alliance (or any other alliance for that matter).

Among "real" lounges, I agree that BKK (Thai *G lounge) is about the worst I've ever been to - it's a perfect place to catch malaria from all the bloody mosquitoes. But even LHR (UA RCC) is pretty pathetic.....dark and dingy... I would expect it to be far better. In LHR, the BA lounges ("Terraces") are superb (specially the Concorde/First Class lounge). In fact, BA has the best collection of lounges around the world.

My favorite Star Alliance lounges are SFO and NRT (United lounges and both relatively recently opened). Another one that I like is MEX (although I haven't been there for a couple of years, so I don't know it's current state). To me the most important "amenity" in a lounge is large windows / abundance of natural light. All three of these lounges have that. After that, I rank other amenities like internet access, peace-and-quiet, shower facilities, food, beverages, etc.