I would wager that for most travelers, carry-ons are the piece of luggage that gets pulled out most. Sometimes it's used in conjunction with a checked bag for longer trips or family travel, other times it's used as your main piece of luggage along with a backpack or tote bag . Whatever the use case, carry-ons are earning nearly as many frequent flier miles as us, and for that reason, you'll want to find one you really love. Our team here at Condé Nast Traveler takes that mission seriously, and we are constantly testing new carry-ons as they come out to see how they stack up to our long-time favorites. One of the main things we consider when testing a new piece of luggage is its functionality—how easy is it to get something out? Is there a pocket to stash last-minute additions? How smooth are the handles and the wheels? Then, there's the size. Is it decently light on its own, before its filled with clothes and shoes? Does it have enough space for a long weekend's worth of items, at minimum?…