I am new to these programs, and my flight is always the Athens-Munich ale re tour, with a Lufthansa flight (booked via the Lufthansa website). I fly on the economy class, with my hand luggage only.
I have a Miles & Bonus (Aegean) and a Miles & More (Lufthansa) frequent flyer card, both on the basic tier (I didn't have any upgrade).
Which card should I use in order to maximize the miles I earn?
Edit: I am only interested in using these miles to book my next ATH-MUC flight with Lufthansa, via Lufthansa website.
Aegean has these rules:
For Lufthansa, as @jcaron said, you earn 4 miles per euro (src).