Go to the Ministry of Manpower website http://www.mom.gov.sg/employment-agencies
Scroll down until you see Employment Agencies and Personnel Search (EA Directory).
Click and see new webpage.
Scroll down until you see Agency Experience.
Select More than 2 years (2xxx Agencies) (logically should include those 5, 8, 10 years, but you can always try them 1 by 1 to compare the list) and if you are looking for Less than 2 years (8xx agencies), just select accordingly.
After select Agency Experience, scroll down further and click Search Agencies.
When new page appears, you see Download (with a little Excel Icon on it), this will download the excel sheet which contains the various information for the agencies including their transfer rates, retention rates, etc.
Make your own judgement from there and decide which agency you want to look for.