I know of no standard credit card that gives access to a First lounges. If you just want general lounge access then the plat charge is top of the heap for general lounge access irrespective of carrier.
After that, probably a diners club card.
Then just shelling out for priority pass full membership
Next would be paying for enough flights with *A and crediting to Aegean. There's no similar cheap way to Oneworld gold but you might be able to status match it...
With your travel pattern, maybe AFF membership and a discounted QP would suffice?
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