If you like *A, then I 2nd AV for earning/burning miles, but I like Aegean for how easy it is to get *G.

There's no real need start an account with a OW or ST airline, since you can credit AA/BA/CX/LA/QF and AM/AF/DL/KL/KE to your AS account.

Among OW, AA and BA are tops for earning/burning.

One thing to consider... you COULD forsake your AS account for an AA one, where you can credit all AS and OW flights. However you'd of course lose the ability to upgrade on AS.