From the looks of pictures anyways, it seems as if...the Sheraton is a nicer looking property, each seem to have between 20-30 suites.
I don't know how far KL Central is, but I can't imagine it being any more than 5-10 minutes, please correct me if I'm wrong.
Walking distance is always good, and the Westin seems to have everything around it...but if one jumps on the monorail for 5 mins and gets to Central KL and walks around...is that really that huge of a difference? Hmmm, something to consider on my part anyways.
Sheraton is rated very highly on TA, and the Westin is not too far off. LM seems to be rated lower, but it's just nice to have great options like this.