It is generally better to sit as far forward as possible. In most cases you will be served first by the cabin service crew. This also means your meal choice should be available. By the time the cabin crew have made their way to the back of the aircraft, often certain meals will no longer be available. Also your meal tray will be cleared first. There are some exceptions though. A few airlines start their cabin service from the rear of the aircraft. If this is important to you, you can probably find that information online.
The best reason to sit as far forward as possible is you, disembark the aircraft before the people at the back of the aircraft. This can be a double time saving as you will likely end up at passport control before the people who were sitting behind you.