WSalam - As you are planning to buy for a long route car which means more wear & tear, I would suggest to go for a vehicle who spare parts are easily available and are cheap. I would suggest Margalla, its very comfortable and lot of its parts are interachangeable with cultus. Plus like most Suzuki cars, its engine is simple and quite reliable (Dheet to be exact)
Sunny & Corolla are great cars but spares are hard to find, specially 88 corolla are very hard to find in good condition and almost obsolete. Recondition one are quite expensive.