For me:
- Premium Economy, Business/First Flatbed, First Class Suite
- Crashes
- Overall reputation actually making a difference for demand
- Baggage Fees
- Toilets (to increase reputation, but they take up space)
- Galleys (to discourage scam IFS, as they take up space and you need more the more items you sell)
- Better demand system (I mean, JFK-LHR has higher biz-econ ratio than say, JFK-BCN.)
- Better deliveries - less frequent and multiple airlines can't get planes all at the same time after a certain number of deliveries! Very important, this one.