Having the good fortune to do both EBACE and the NBAA I'd argue that if you're a European Operator and can only afford one then make it EBACE.
NBAA's great in terms of parties and freebies, but in terms of who you'll see and the stuff you really need to see, then Geneva provides all of the relevant information.
The majors are there, the airports, handling agents and operators are all represented and you'll see people you know.
Whilst at the NBAA you might have the opportunity to meet up with some of your American contacts, you'll see all your European ones at EBACE. In the current climate, that's where the business is!
It's improved since the first run, immensely. But if it's parties and freebies, then the States is the one.
See you at either!!