I have stayed at all three in the past year. To me, the Regent and the Hilton are similar in service levels. I find the physical facilities at the Regent a tad better. I haven't stayed on the Club level at the Regent, so can't opine.

In general, the Regent is more of a mainstream hotel than a true luxury product. Think a Marriott Renaissance property or a Westin. For a Hilton, the S'pore property is pretty good.

The Four Seasons is a luxury product, although I am not a huge fan. Too spoiled by the hotels in Bangkok, I suppose.

The price points are pretty indicative at these three hotels of the quality levels. The Four Seasons is the most expensive and worth a 30% increase over the Regent. The Regent is more than the Hilton.

All that said, when I look at value for the dollars that my clients will pay, I usually stay at the Regent. A couple of clients will pay for the Four Seasons, so I stay there in those cases.

None of the three are a "bad" hotel.