I operate a mixed fleet.
Year in the game i am in is 1993.
ATR-72 for regional routes (less than 500 miles) to rural airports with less than 100.000 passengers.
737-500 for my African network. Small type with plenty of range. Will be replaced by either A319, 737-600 or 737-700 (i will choose when they are available).
A320-200 for most of my network. Carries more passengers than most other aircraft available, only aircraft in it's class that has more range is the 737-300. The 737-800 isn't available yet, but i will decide on a replacement when it is available.
757-200 for longhaul out of smaller hubs. Nothing else available with same range.
A310-300HGW for long haul. Cheaper than a 767-200ER, and slightly faster. Fulfills all my range requirements.