cravings
Before moving to Hong Kong I scoured the city to ensure it had hamburger joints, pizzerias, fried chicken, and a few other foods I get cravings for from time to time.  I've expanded the cravings to not only include Western cravings but also any non-Chinese cravings, like Japanese, Indian, Thai, etc.  Most of these places in the central to tin hau "corridor" and Tsim Sha Tsui areas.

HAMBURGERS
All things considered, Hong Kong has quite a few good hamburger restaurants scattered throughout the city.  These primarily fall in two categories: the higher end restaurant that features a hamburger on their menu (typically catering to the western crowd) and lower end restaurants offering a hamburger as their main menu option with a few other fast food options.  Even in the lower end there seems to be two separate categories. The truly fast food restaurant and those with fast food ordering but an individually prepared meal.  The latter seems to be the sweet spot in Hong Kong, where you can eat a decent burger meal for under $100HKD.  

I joined a hamburger meetup group to sample the higher end burgers  and have been tackling the lower end places on my own.

PiZZA
Good pizza, at least the kind I like, seems to be limited to northeast USA.  Los Angeles had a pizza problem with few pizza parlors getting anywhere close to their northeast counterparts...so it's no surprise that it's a similar struggle to find quality pizza in Hong Kong.  There are few fast food pizza places - where you pick a slice, it's reheated in the oven, then ready to eat.  There's a lot more sit down Italian restaurant acts with a pizza option - these pizzas tend to be of good quality but a completely different style than the thin crusts back home.

western
Hong Kong has many restaurants catering to Western tastes but most of these places are also heavily frequented by locals - I assume it's no different than a packed PF Changs would appear to a Chinese, although Hong Kong restaurants' Western offerings are a little more authentic to Western cuisine than PF Changs is to Chinese.  Hong Kong also has diners that offer a fusion of Western and light Asian food offering everything from spaghetti to hot dogs and steak sandwiches.