FRA and LHR are both large airports so give consideration to connection time at each. If you fly from LIN to FRA you will 99.9% of the time get a bus to gate arrival (and departure for that matter) which requires more time for connection (add about 20 minutes). LH PE is actually a nice product and you can buy lounge access at FRA if you have a long transfer. LH's M&M program does have higher earnings for PE "Premium Economy Class E, G: 1.5 x distance, at least 750 miles N: 1.0 x distance, at least 500 miles"


BA's main advantage is a later departure both ways which can fit more people's schedules. BA's Executive Club has similar earning rates for PE (WT+) with 150% with 750 minimum on W fares and 100% with 500 minimum for E & T fares.