BUD (MA) or VIE (OS) comes to mind as possible hubs. Depends on your destination and alliance affiliation (MA=OW, OS=*A)

MA serves BEG, TGD, PRN, SJJ, TIA, ZAG, SKP, SKG If you want to go to the Eastern Balkans, too (RO, BG) they serve SOF, BUH, TGM, CLJ

BUD is very easy for transfers, the flights are shortish hops.