txlflyer

Having been on at least a dozen flights on the 747-8 and even more on the LX 340-300 I would definitely go for the LH flight. The upper deck is normally pretty quiet and the service is quick. The bigger screens and the better entertainment program, as well as the better food you will find on LH. I also love the hot towels on LH, they are the best out there ( having lived 8 years in Japan I am quite picky). The amenity kits with Korres products are also better on LH. I had several issues with unprofessional crews and broken seats on LX lately and think that their business class is just too old and outdated. I do like the new LH biz seat and it gives me a solid 6 to 8 hours sleep on long distance flights.
So if I would be you, I would go for the 747-8 flight via Frankfurt. As for pilot strikes, they will rebook you on other flights or airlines without any problem, so that should not be an issue.