Insertsoul, it depends on what goal that you want to achieve.
If you want to create a real-world airline that mimics the real world situation, then go for the A330-200! It is the best of all other Airbuses and Boeings, it certainly beat out the 767-300ER all over! While A330-300 is a no-no, because there is the 777-200, however it still retain its commonality with other Airbuses as an advantage. A330-200 is sure to be the most brilliant aircraft Airbus ever thrown to the market!
A340-300, four engines, under powered, extra maintenance cost, pre-production series has weak structural strength (which resulted in lower airframe value), this is one of the reason why i don't want to buy A320-200 in world 4 before 1994, where the A320 has been improved (eventhough it is not implemented by AM). The only good thing about A340-300 is that it has the quietest cabin in the sky at the first time when it was in the market.
I don't know how will this aircraft behaved in AM, but i think every aircraft will work pretty well in AM, only one giving you less profit than the other one, but will not cause you to lose the competition.
y Airline is: Star Air Indonesia (W4)
My Aim is: Creating a real-world like airline with reasonable flight frequencies and rational aircraft type of fleet, by not necessarily hogging the game's nature/bugs/lacking.