Preferred luggage
In answer to your question, I think it depends on what you'll be doing and what type of vehicle you'll be traveling in, and where you'll stay if you stay outside your vehicle once you get to your destination(s).
We have always used bags with wheels, and depending on all of the above, the choices have varied.
For trips by bike, we use Lowepro camera bag inserts for our clothing & toiletries. Two of these fit into the XL or XXL REI or Eagle Creek duffels during flights and then they are laced onto the tops of our Touratech boxes when we're enroute (our Lowepro camera bags stuffed with camera equipment go inside the Touratech boxes).
For trips where we were on a bike with a chase truck, we used rolling duffles with many sections and pockets (easy to segment stuff for quick access in the truck). Eagle Creek bags are awesome (as are their pack cubes for keeping everything really well organized, a must for me!).
For trips where we were staying in our FUSO, we preferred duffels that folded down to nothing, and that could be grabbed and stuffed quickly should we need to bug out. The REI and Eagle Creek duffels are rugged, lightweight and the companies stand behond their products.
When we fly in someplace and will rent a vehicle and be going in and out of hotels, we prefer either small rolling bags (remember that many country's hotels either have no lift or very small ones) or duffels that fold completely flat.
Hopefully you will find that one of these options serves you well.
