Anonymous wrote:Lightweight, smallest you can get away with.
+1
I'd add that it's probably not worth stressing or overspending. You've already traveled some, so you have some idea of what you like and don't like.
Features I like:
The two-wheel style (as opposed to 4 wheel)
An exterior pocket that will accommodate a laptop, and a second exterior pocket for other tiny things.
More generally, I like a carryon that will allow me to put as much weight as possible in that wheeled bag, and as little as possible in my purse/briefcase/whatever.
I also prefer a single handle (as opposed to the typical U shape), but that feature is really hard to find.
I would also try to pick something you'd be comfortable checking in a pinch.