You should check on the Aegean website how many miles you will receive for the airlines and sectors you fly and base your decision on that. It is potentially far easier to gain status on Aegean than on the Lufthansa Group airlines but then if you will not fly enough or on the ticket classes that award miles then there is no point.

Also, Star Gold status is really no longer seen as the status level it previously was. Many airlines, and Lufthansa Group were one of the first to do this, favour their own status holder above Star Gold members when it comes to upgrades or even seating. Seating benefits used to be enjoyed by Star Gold members across most Star Alliance airlines but that is long gone, as is the extra baggage allowance on the cheaper tickets or when only one airline is on the ticket. The Star Alliance airlines are finding ever more ways to compete rather than be in alliance.

That said, I prefer the Aegean program to any other Star Alliance program. Award flights are often at a lower mileage level, Europe<->USA return in business 90,000 compared to Miles&More 105,000 but then Aegean does not have the discounted special offer awards that Miles&More sometimes has. Depending on the booking class, sometimes you'll get more on Miles&More than you do on Aegean, sometimes the other way around. In any case, the change of Miles&More this week to being revenue based can generally be seen as a yet further devaluation of that program that will lead to even fewer miles being awarded. This makes the Aegean scheme relatively more attractive. Take a look at Miles&Smiles from TK too, as some people like that scheme more.