I recently had the opportunity of flying in C/J GVA-LHR and LHR-GVA on each of LX and BA, so have been able to make a direct comparison. I have to say that BA wins out by many miles in respect of the on-board offering.
In LX I was allowed to choose anything I wanted from the BoB, but it looks really unprofessional to get cardboard boxes dumped on your table and none of the offerings were terribly appetising.
On BA you get a proper tray with a plate of cold-cuts, cheese and a bit of cole-slaw. It's not a gourmet meal, but infinitely more attractive than the LX offering.