LH is 2-2-2 with some non-LH configurations peppered in from leases and taken over planes outfitted for other airlines.

LX and OS have same seats, some slight differences in configurations between types.

Since you are not interested in thrones, I agree with Deckter, you should not take seats as the decision factor, flight times, aircraft type and I'll add, soft product and transfer airport will make more of a difference.

LX is A330+777. OS is 767+777, bear in mind with the 767 that there are no pairs on the side, only in the middle section - the whole cabin is 1-2-1

LH you can either take a flight via FRA, which will give you the option to fly with the 747 in the upper cabin, but will mean transfering through FRA and a very long layover (flying A340 from JFK, which is eh), or
to take a flight via MUC, which is pretty good with combo A380+A350, but, at the cost of an extremely long layover.

In comparison, LX gives you a decently long layover, but arrival in Shanghai at half past three in the morning.. OS offers a short 1h connection (which is fine in Vienna) and an arrival just before 6am

All things considered, I'd probably go for OS, or LX if it was significantly cheaper