Day 17 of Bootsnall’s “Plan your RTW Trip in 30 Days” addresses what kind of luggage you should take…suitcase, backpack or hybrid? This seems like a pretty obvious choice to me, but maybe it wouldn’t seem that way if I had never traveled long term before. In my eyes, a backpack is the only way to go. A rolling suitcase may seem practical…until you’re faced with miles and miles of gravel or cobblestone. That hard-shell might seem like a good choice…until you can’t stuff it in your assigned locker at a hostel and therefore can’t lock it up. For these and a variety of other reasons, I’d recommend going with a backpack. It’s just easier to sling a backpack over your shoulder when you’re hopping from hostel to hostel, train to ferry, bus to plane. Having said that, don’t just run out and buy the cheapest backpack you can find. Take your time finding the one that is right for you. Remember, you’re gonna be hauling this beast everywhere with you so you need to make sure it not only fits your body correctly, but is made out of a very durable fabric, has enough space for what you need, but not too much, because that can also cause discomfort, and fits any other specifications you may want. For instance, I prefer mine to have a raincover, be top-loading and front-loading for easy access, have a separate compartment for muddy shoes, and have limited extra external pockets as they tend to be a target for pickpockets.
You don’t have to spend a ton of money, but don’t skimp on your backpack because it will be such an important part of your trip. Check out the sale rack at REI, LL Bean, Northface, etc. An outdoor store is more likely to have a super comfortable and durable backpack than say, Walmart, which is where I got my first travel backpack. It did alright, but after about 6 months of backpacking, it had 2 holes and one of the stabilization stays had ripped off. The straps were starting to rub and it smelled like a foot (though that last detail probably had more to do with the fact that I’d spent 6 months in the super humid Central American climate where nothing ever seemed to dry. Stay strong and travel on!