I do this route on a monthly basis, oftwn twice per month and usually do one trip in LX F and the other one in LH F for the sake of comparison. By all means, LX F is a very solid product and better than LH. But for this very flight (and LH 510-511 FRA-EZE-FRA), I find LH experience to have improved a lot this year comparing with 2022. LX does not offer caviar that seems to be the highlight of F experience for many pax who travel with LH. However, on LX one gets balik salmon which is equally good. Seat comfort on LX is very good, especially if you can get 1A/K or 2A/K single suites. The seats do show their age now on LX, though not as dramatic as LH F cabin on B748 does. As for the food, I find LH F to have improved a lot on GRU/EZE segments. It's not on par with LX, but much better than what it used to be. Also, F departure service from ZRH is a very relaxed experience. Of course, if you are in FRA FCT, you get the same benefit as in ZRH (private passport control and transfer to the aircraft). One benefit of LH to GRU is that often arrives before most of other European flights do, so immigration in GRU is relatively fast for LH pax. However, LH to GRU is often prone to delayed departure the next day if B748 has mechanical issue.