I've stayed at both the Le Meridien and the Hilton. I prefer the Le Meridien. Both hotels have good service. However, I like hotels with a more classical, traditional decor.
Also, in comparing the executive lounges at both hotels, the Hilton in the mornings and during the evening cocktail hour can be quite a zoo. This is exacerbated by the television being on constantly which disrupts the tranquility in a lounge that I look for. The executive lounge at Le Meridien offers peace and quiet, and also more personal service.
But if you like hotels like the W, then Hilton is a good choice.