Rather than what others are carrying, consider what fits your needs and just do it. Rick Steves notes that each option has its advantages and disadvantages:
Rick Steves: Tips for Choosing the Best Travel Bag
By Rick Steves
A fundamental packing question is your choice of luggage.
- a carry-on-size soft backpack, an internal-frame backpack,
- a carry-on-size soft-sided bag with wheels,
- a carry-on-size hard-sided bag with wheels, or
- a carry-on-size rolling backpack.
Each of these options has its advantages and drawbacks. Before you
decide, consider these factors:
External dimensions: Is it small enough to work as a carry-on? (If
not, are you willing to put up with the likely delays and extra fees
that come with checking your bag?)
Weight: The lighter the better (even rolling bags need to be carried
from time to time)
Comfort/Ease of carrying/Mobility: Consider not just airport terminals
but uneven surfaces (cobblestones, gravel) and stairs, and the
advantages of carrying your bag while still having both hands free…as
well as how easily you can carry 20–25 lbs on your back
Efficiency of space: Look for the most (usable) capacity within the
external dimensions
Expandability: A nice option, especially for the trip home
Quality of materials: Go with a well-established and/or well-reviewed
brand
Cost: Worth considering, but not at the expense of decent quality
Frankly, no one bag is ideal all the time for every traveler. When
weighing your choice of bags, think about which of the...factors
matter most to you. Go with the bag that meets your most important
needs, and make sure its downsides are ones you can live with.