Luggage preferences vary a lot from person to person. Some people want to bring LCD screens and scuba gear, and one time I chose to bring a PS3 with me. Some people are embracing a minimalist life as part of their DN journey and like to fit everything into a small bag and a carry-on. Staying in hostels and moving around a lot would suit a backpack better while suitcases make more sense if you’re only traveling by air and not moving much.
You don’t need to stress over this. If it turns out you have the wrong type of bag, a trip to any mall will give you plenty of other options. You’re not going to the middle of Africa in 1850, after all.
You need to be able to lock your backpack or suitcase for extra peace of mind during transit or in shared accommodations. It also prevents corrupt airport staff from planting contraband in your bag. Get a padlock with a number combination so there’s no key for you to lose.
Whether you have a backpack or a suitcase, packing cubes will enable you to jam more in, organize and separate your things, and make everything easier to find.
Clamshell style makes for easier packing. If you get something that forces you to pack through a hole in the top, you'll have to dig through all your stuff to find something at the bottom.
Many of the cheap airlines in Asia make customers pay extra for checked-in baggage. If you are not bringing many possessions, there is value in making it fit into a smaller backpack that you can carry with you on the plane.
Some small backpacks that I've seen praised by nomads are:
If you’re packing a 17 inch laptop be careful because some laptop pouches are too small for that.
More backpack comparisons by digital nomads (switch to the ‘Backpacks’ tab)
The first instinct is to sneer at suitcases as if they're not 'hardcore traveller' enough. But in reality, most of us are going from city to city, from plane to car & plane to train. We’re not hauling our things through the hot desert or dense jungle. There are always people nearby eager to carry bags for a few coins. Laptop, passport and more valuable things can go into a small daypack, while bulky less valuable items go in the suitcase.
Suitcases are easier to pack (personal preference), far easier to dig through, better protect their contents, if your luggage is in the bottom of the bus and encounters meddling hands, it's not that easy to get into.
Get a hard shell suitcase with big wheels. It’ll hold it’s shape better and be able to take more of a beating while protecting your electronics.