Which class is best for long-distance trains in Sri Lanka?

Second-class reserved is often seen as the best option for travelling long distances. It gives a steady level of comfort. You can also open the windows, which helps when taking photos.

First-class comes with very good air conditioning. Still, the windows are sealed, and the glare gets in the way of landscape shots. Third-class reserved costs less. The trade-off is that the seats feel thinner and less cushioned. Second-class ends up as a good middle ground. You get the local feel, decent comfort, and clear views of the countryside.