hong kong people are very fashion forward. i've seen a lot of lv- in different shapes, sizes and prints. i don't know if there's really any one bag that is hot. i see a lot fo the neverfulls and dentelles being carried around, though. so i guess in terms of popularity- i'd say good, old mono is on the top of the list.
For the general crowd, it's LV monogram, and for the more fashion forward (and willing to pay), it's anything LE. And HK ppl are never behind, so it's all Dentelle, Olympe, and the occasional Mirior still.
I think if you carry anything LV, you'll blend right in.
I just came back from HK and I must say that I'm getting sick of mono Speedys (all sizes), BH/BV, Neverfull (all sizes...although IMO a lot of the girls there are much too small to be carrying GM) because 50% of people carry those bags. For me, blending in is no no, I'd rather get something unique. I see lots of Noes too.