Unfortunately the true answer to this is bad.
SG girls in my experience are by far the worst of all nationalities I have tried.
Unskilled, lazy, boring and passive.
Although I have only slept with four SG girls, they would rank among the bottom five of the worst sex partners I have had. The worst is still that Hong Kong prostitute that I lost my virginity to. But the SG girls were terrible in that it was almost like they were always directionless and seemed to be waiting for me to take the initiative.
They would just lay there and look at you like how a cow would look at you with those blank, passionless eyes. Almost like they had no brains or something. But this only applies to the SG Chinese girls. The SG Malays are actually quite good so I don't count them as Singaporean in that sense.
I hate to admit it but by far the best and most aggressive sex partners I have had are still the Europeans. No comparison at all to SG Chinese girls. In terms of skill and enthusiasm it is like comparing eating at Raffles Hotel to eating at a HDB coffee shop. The SG Malays are almost as good as the Europeans but with the added advantage of being more "local".
The strange thing is this, Malaysian Chinese girls are still better than SG Chinese. Ethnically they are identical. So I suspect that the cause of the decline in skills is environmental. Maybe SG girls are wealthier and better educated and that makes them less enthusiastic and more apathetic to life which affects their sexual mentality? I don't know. But I suspect it.
Other notable ones are the Japanese/Koreans and Mainland Chinese. It is hit and miss, but I would say on average they are quite good. Infinitely better than SG girls.
So I would rank them like this:
1) Europeans/whites etc. (No contest.)
2) SG Malays (Very skillful and unselfish. Very nice people too)
3) Japanese/Koreans (Some average,some quite good but still a bit passive)
4) Mainland Chinese (I think they can be quite skillful but I don't like their money minded mentality)
5) SG Chinese (Unskilled and very boring.)
I have also tried one Indian but she was average so I won't pass judgement on them yet.