I think it depends on what you are looking for, (price vs facilities vs service vs location vs ambience) but my personal favorites are:

SIN - Ritz Carlton, nice airy rooms with great views. I would choose it any time over Raffles which IMHO is overrun with tourists not staying at the hotel, and while they have security gates meant to keep the unwashed out of the residential area it is very easy to bypass them. I do think that Doc Cheng's restaurant and the Indian buffet are excellent features of Raffles.

BKK - Sukhothai, a well kept secret in a very lush setting and a wonderful air of tranquility. Excellent bathrooms. Nearly everyone who knows only a little about BKK will say that the Oriental is supposed to be the best hotel in town. I think it is getting tired and like Raffles is far too public for my liking. A close second for me is the Regent which has a great swimming pool.

SYD - personal favorite is the Sheraton on the Park. Primarily for the location but I also like the amenities in the room (like the CD player) and they have good bathrooms. Quite a number of small boutique hotels have opened in the inner Sydney area and they look quite interesting (at least on paper). I'll be giving one of them a try on my next trip.

MUC - never been so can't say.