I have flown LX longhaul J several times, but not OS. LX J service is a bit mechanical IME, but the food is edible, the wine very drinkable, and the amenities solid for a J product. The seat is pretty slanted, but I sleep fine in slanted seats on my side. I have heard great things about the OS onboard catering and they are top 3 on my list of J services to try. One of the advantages of OS is that J is the top class onboard.

I have flown both shorthaul in J on both on trunk routes like VIE-ZRH, ZRH-FRA and both hubs to London and they were all great. I have been lucky in that all of my intra-Europe flights on LX and OS have been very empty in J, so I get amazing service and the crews were all very friendly - there was no rush for meal service, and I learned a lot of great stuff.

It also happens that Austria is my favorite place in Europe, so I get all excited about anything Austrian