I see your points, and the SQ F longe in SIN is better. Coming from the experience of domestic and international UA RCC lounges, this what I like about it were:

1. It was NOT full of passengers. Admittedly I was there from 7 to 10pm waiting on the 11 pm shuttle to flight to SIN. But I wonder if it ever gets "full".

2. I thought the food was tasty and there was a nice variety of drinks. I actually liked the staff was there to clear, but otherwise left me alone.

3. Nice long hot shower... After running around KL all day, that was nice.

4. The chair. Silly, but that was fun.

That being said, connectivity was so so. There were some workstations but not as much as SQ SIN.

As part of the overall F experience, checking in at the downtown station, the express pass through the immegration line, and the cheap price ($25) for the whole deal made it a nice addon.

SQ SIN and MH KUL are flukes in that you can get in with the KIL-SIN shuttle flights.
Otherwise I don't think I could afford an F ticket anywhere else. That aside, of the rest (especially *A carriers) which would you recommend?