Amansara is VERY small...Almost too small. I like that you can walk across the street to Raffles.
Amansara is great make no mistake and good for three days. Just venture outside of the 'walls' and eat elsewhere.
Raffles is much larger and GREAT pool, excellent resturants choices too.

The two hotels are not really in the same league however.

If I ever venture back I'd do exactly what I did last time. Stay at Amansara and enjoy a few meals outside of Amansara.