According to the Austrian DerStandard the EBU favours Vienna's Stadthalle to host the next Eurovision.
Song Contest: EBU soll Wien bevorzugen - ORF - derStandard.at
Basically it says that from the capacity it is the only hall in the bid which could host a green room on the floor, something we seems very important for the EBU
Furthermore Vienna would attract more sponsorship money because it already has a strong image.
For ORF it would also be the most convenient choice since they wouldn't need to relocate and could spare lots of their own money.
On the other hand, Innsbruck still has the deeper pockets, whereas Vienna has no money at all.
The tabloid newspaper "Österreich" seems to play a game on their own, by spilling rumours and stating in each of their regional editions a different favourite to host. Still, many ESC blogs and websites think that Österreich/oe24.at is a legit source of information. Well, it's not y'all!