I haven't been going out for dim sum much in the last few years, perhaps once every six months or so, but recently I visited two places within the span of two weeks, which gives me a basis of comparison. Both visits were on weekdays, so the crowds were non-existent, but may have also played into the offerings.
First up a week and a half ago was Asian Pearl on Stockton Boulevard. Went with a group of 8, about half of whom were Chinese, although no native speakers. The selection was pretty standard, and all were very solid. I was not terribly impressed by the dan taat (egg custards), because the filling was firmer than I like (vs creamy), and I prefer a pastry crust rather than a shortbread crust. The food quality merited a solid 8 out of 10, but the lack of variety in the selection was only worth a 6, for a 7 overall.
Today we hit Hong Kong Islander, near Executive Airport. The group was smaller, but 3 out of the 4 are Chinese (including a native speaker). The selection on the carts was more varied than at Asian Pearl, and the execution was possibly even better. I didn't catch the name of the one dish that really stood out, but on first glance it looked to be a fairly standard shrimp cheung fun, but wrapped inside along with the shrimp were some crunchy noodles that somehow did not get soggy. It was different and it was mighty tasty. In sum, food quality was an easy 8, variety was also an 8, for an 8 overall.
On weekends, both of these establishments are known for more. More variety, more people, more more. I haven't been to either one on a weekend, so I can't say how a visit on a Monday or a Thursday stacks up against Sat/Sun. I do know, however, that I'm much more likely to hit HKI for lunch than Asian Pearl.