I thought about this a while ago when discussing what would happen if he lived and became Emperor. I think in part it depends on how the War of the Spanish Succession is ended and what becomes of his uncle the Archduke Charles. That would affect the kind of alliances Austria would make. Though I would assume he'd probably take a wife ASAP as he's in the same position as Louis XV, he's the last of his line and if he dies without heirs the throne would fall to a cousin with claims to Spain and/or some Italian state. So probably someone about the same age who would be ready to give him a son.
So two German princesses fit the bill;
Auguste Johanna of Baden 1704-1726 OTL wife of the Duke of Orleans and she did give him a couple of kids.
Anne Christine of Palatine Sulzbach 1704-1723 OTL wife Charles Emmanuel III of Sardinia-Savoy.
Assuming an alliance or at least rapprochement with France was desired and that there was still an Orleans Regency then perhaps Charlotte Aglae d'Orleans 1700-1761 OTL wife of the Duke of Modena.
Elisabeth Charlotte of Lorraine b.1700 or her sister Marie Gabriele b.1702 both died in 1711 of smallpox but its after the POD so if they lived they could work as a gesture towards France without marriage to a French princess.
The best Italian match would probably be Enrichetta d'Este 1702-1777 wife of Antonio of Parma, however their marriage was childless though it's not clear whose fault that was.
Another interesting choice would be Maria Clementina Sobieska 1702-1735 who OTL married the Old Pretender.