I've taken both flights in both directions in J. I've noticed only minimal differences in service levels on the flights, personnally i think just pick the one that fits your schedule better. I tend to like the later LAX-HKG flight because it has worked better with my personal sleep schedule, and exhausting myself to the point where I sleep for more of the flight. My only caution with the later flight (which I think is actually 12:15, not 1:30) is that if you are connecting in HKG to SE Asia connecting times can get cut pretty tight if there are any delays (winter months headwinds can really screw with the flights TO Asia). The other big advantage to the later flight is that the TBIT at LAX is less crowded than for the earlier flight, although in J that is not a big issue, if there is a long security line, they will give you a pass to use the crew line.

On the return from HKG again, either decide if you want a full day in HK or want a half day. I found it odd when returning on the 11:30p flight last week that we were served dinner after take off from HK and then BREAKFAST on approach to LA even though it was evening LA time. Last year on this flight I had two dinners.

Not sure if this helps at all. Personnally i like the upper deck, if you can, get the middle exit row upstairs for more space.