As a loyal LH customer (Senator since 2000) I have over the last three years moved more and more of my business to Swiss.
From my market, Swiss offer excellent fares, product and ZRH is much better than FRA. MUC on the other hand, is a nice experience.
The SEN lounge at ZRH never gets as crowded as the FRA and MUC lounges.
However, I look forward to testing the LH First experience in the new cabin and with the FRA FCT which I have never done. I have been in LH First three times, it was splendid! However, I was upgraded at gate so I did not have a chance to test the overall experience.