AF A380 and KL A330 will be on old C seats, angled lie flat.
LH B748 will have new C guaranteed and the B744 has a good chance of new C (full flat) by this summer.
On the outbound overnight flight the flat seat would be most important to me, so I would pick the LH option.
That said, AMS and CDG are much easier airports for (short) connections than FRA.