2 hrs enough connection time at NRT?
 

we are looking at flights for China trip in early fall...haven’t yet decided on United or American ..we can fly fromLAX or SFO. Trip will start in PEK and end in HKG. Both itineraries cost approx. the same.
Return flights ticketing with UA - is HKG/NRT/SFO. There is a 2 hour connection time at NRT to leave Japan Air flight from HKG and get thru customs and security (I assume) and get on ANA flight. We will have business class seats - maybe that will help if they offer expedited security check. Positives for UA/ANA - Polaris on way over ( experienced it on SFO/SYD flight last year-good) and despite 1 stop gets us home early afternoon with only 2-1/2 hr. Layover in SFO.
The American flights over and back are nonstop(LAX/PEK&HKG/LAX) only drawback is a 5 -1/2 hr. Layover at LAX coming home with arrival at home at midnight.
Guess I have 2 questions: Is 2 hrs at NRT enough time to change flights and is there much difference between AA business class and ANA business?
thanks for any help.

2 hours is ample time for Narita transfers, even if it involves changing terminals.

ANA Business will offer a drastically better soft product than AA Business (or other US-based carriers.) ANA catering ex-NRT is also excellent.

OP's Japan Air is probably Air Japan, and has an NH flight number.
In that case, the flight arrives at terminal 1. So, no terminal change.

I've done the NRT connection MANY times, and you will likely have an hour in the lounge ;)

My one and only ANA 777 flight was to SFO, and in Biz it was a very nice ride :)

- currently approx. $5000each ? That is way too much for business class to Asia from the west coast.
you can drastically reduce the pricing by flying via Korea .
Sample: https://goo.gl/flights/GRsFh