Each have their merits, and it doesn't mean these restaurants are bad, but I think their "names precede the truth" (名過於實 | Cantonese: ming gwo yu sut | Mandarin: ming guo yu shi) as we say in Chinese...
Hutong (and Aqua) - all about the view. Hutong's lamb ribs I love, but everything else, um, I don't have polite things to say about...
Xi Yan - there are better private kitchens
Luk Yu - more about the atmos than the food. There's better old school dim sum at Lin Heung
Mak's (Wellington Street) - Ho Hung Kee is just as good (+ many others) for wonton meen
Sang Kee congee - congee is thin, watery and overcooked nowadays (used to be better)
Tonkichi - the waiting list/line is a bit ridiculous for an inconsistent product
Lung King Heen - it's up there with the best, but it's not the holy grail of Cantonese food, so stop saying it is
Ovologue - gwailo (ie. foreigner - equivalent to gaijin in Japan and farang in Thailand) posing to be innovative and 'authentic', whatever that means (and however that matters) - gold leaves and abalone in teeny weeny portions on fancy schmacy crockery with sauces that don't taste or don't match, and sometimes cold (when it's not supposed to be) - it's just not good food
Bo Innovation is also one of the most talked-about places in Hong Kong - especially since it gained its two Michelin-star status, but I haven't tried it yet, so watch this space... [edit: I have now - see here]
These are just some quick notes off the top of my head (and to get off my chest). What have your experiences been like? Any to add/subtract? Bring it on. I'm geared up for hate mail. (Though I should reiterate that each of these restaurants have their merits and obviously exist for a/some reason(s) - some more understandable than others... and that these are of course, my personal, humble opinion.)