Decision on what type of luggage to bring depends on the nature of a trip. For city-hopping a suitcase on wheels will do fine, especially if you will cover the distances between airports, train and/or bus stations and hotels by taxi.
If you are planning a trip to less developed destinations or your trip involves a lot of walking, bring a good quality backpack.
Before buying a suitcase or a backpack you need to consider the quality and brand of baggage you will be lugging around on your trips. Some give absolute priority to the most expensive suitcases of reputable brands while others find it unnecessary to spend hundreds of Euros on a suitcase or a backpack which will end up being handled by not so gentle airport workers and machines.
We believe that when choosing a backpack it is important to give priority to comfort and practicability rather than a brand. Think about carrying you heavy backpack in 35 degrees Celsius and 90 percent humidity and you will soon realise that you need a backpack with comfortable shoulder straps, good hip support and possibly back ventilation.
In case of a suitcase, price/quality ratio probably plays the most important part. Based on our own experience we would not recommend to invest into awfully expensive suitcases as they too sometimes give in to brutal forces of airport staff and luggage handling machines. Besides, after a few flights even most expensive suitcases will become as dirty and scratched as their cheaper brothers. So the bottom line is - pay attention to build quality rather than a brand.