LH A380 has much larger bathrooms.
In terms of sleeping quality, they are comparable. In my opinion LH bedding is more comfortable, but I agree that LX777 you can enclose your seat a little better, however A380 is so silent...
Food is generally better on LX
Depending how long is your connection (I assume in FRA), ground service is usually better with LH, where you will be driven to your connecting flight if you go to the FCT, which I usually do.
LX E lounge in ZRH is great, however in my experience they don't provide limo transfer from E to A/D where your LHR flight will leave (they do the other way around)

Both are great anyway!