there is no one solution for all needs
consider price, size, volume, weight, toughness, protection, waterproofing, ease of maneuver whilst in check in queues, ease of lifting (does it have good handles on top and side), zip quality, etc
consider how easy it will be to spot on the conveyor belt
ensure straps and seams are double-stitched and wheels are tough and robust and easy to maneuver
synthetic zippers made of interlocking nylon coils may be better than metal zips for durability
check the retractable handle to ensure it slides in and out smoothly and locks in position
at various times of the year, many products can be purchased new at 40% off the retail price, such is the retail mark ups.