Hardside! Hardside! Hardside!
My Top 2 brands are Lojel: a great feature is 4-wheels in both horizontal and vertical standing position, and has key locks as well as combo lock) and Atlantic: I love the off-center deep clamshell design, easy to pack and really protects my stuff, but can only be pulled the 'wide' way, also, the locks on the Atlantic make me uneasy, they seem a little weak, and I usually use a strap for some extra peace of mind.
Eminent is a good third choice for reasonably priced hard side.