Best Backpack for Travel? Need Real Advice

The best way to choose is to visit REI, where you can try on backpacks with expert help to fit it to your body. Also, they have weights they can put it the pack so you can get a feel for how the bag will actually work for you. If you don't live near an REI store, they have an excellent return policy. Another great source for bags is Sierra, which has far fewer stores (I'm lucky to have one in my little city, and they also have weights you can put in the bags to test their comfort), but also a very good return policy. REI also has videos of how to measure yourself for bag fit. If you need to order bags, you can test the fit by actually packing them with the real stuff you intend to bring. Rick Steves suggests packing up and going for a walk around your city center, maybe getting there by bus.
All of that said, one of the best lines of bags is the Osprey Fairview line. The smallest bag is 40L, which is pretty big. Other good brands are REI, Cotopaxi, Eagle Creek, Deuter, Topo Designs, The North Face (black hole series) and Gregory.
Here's a great deal on a 40L pack from Sierra (only available in S/M): https://www.sierra.com/eagle-creek-tour-travel-40-l-backpack-small-medium-black~p~7gkhd/?filterString=backpacks~d~9669%2Fcotopaxi~b~36230%2C4061%2C5040%2C7155%2C10092%2C33546%2F

I purchased a 28L Cotopaxi Allpa several months ago for my frequent two nighters to San Francisco after reading several people on here raving about the brand. I couldn’t be happier. My daughter has the 35L for longer trips and is extremely happy with it. But as mentioned above, the best advice is to go to REI, load some up and see how they feel!

Do you want a backpack for use as a suitcase or are you looking for a smaller backpack to use when you are out and about during the day?

You need to decide what you are looking for in a backpack. If you want one that is not available in a local store, see if it's available on Amazon because of their easy returns.

Expect many responses here. Need to set criteria for yourself as opposed to item promoted on social media. Important questions: torso size/height and ability. Male or female? Underseat bag (28 liters), overhead bin bag (35 - 45 liters), checked bag? Type of travel: easy going strolls, rainy weather, African safari with wild warthogs playing with your bag? Ease of packing. (Use packing cubes!). Minimalist or maximalist? Airline dimensions. Weight of bag. Computer or no computer?

Look at major players that back their luggage. Examples: Rick Steves, Osprey, Patagonia, Tom Bihn, Samsonite, etc.. These companies have been in the travel business for a while and understand materials and design. Have fun and good luck!

I forgot about Tom Binh. If money is no object, by all means, get a bag from Tom Binh.
I'm pretty sure Samsonite doesn't make a backpack, but if they do, it probably weighs 5 pounds.

“ a solid travel backpack.”

Take a look at Tom Bihn, Red Ox and Cotopaxi. Also, look at Sarah Murdoch’s website for a lot of discussion on packing and bags. Her website is: https://adventureswithsarah.net/. She was a long time guide and writer for Rick.

Don’t be afraid of cheap backpacks like ecohub on Amazon.com - just as long as it meets your criteria. Unless you are savage with your bags, even cheapo bags can provide good service for a while. Nylon and polyester fabrics are good for water and wear resistance.

You've gotten good advice I will only add that if you are looking for a backpack to use as your primary suitcase then make sure you find one that has a hip belt, padded shoulder straps and a sternum strap. The hip belt transfers the weight of the bag to your hips, lessening the strain on your shoulders. The sternum strap keeps the shoulder straps from slipping. Because you want to transfer the weight to your hips the fit of a bag is important. If it's too long or short it won't be comfortable to carry for more than a 1/2 mile. Also be mindful of how much the bag weighs and how much total weight you can carry.

Osprey Daylite Series is a good place to start to get ideas about what you need. Osprey has been around a long time and understands materials, design, and construction. Granted - there are many brands out there. No need to limit yourself. But, Osprey Daylite bags make a good starting point for comparisons.

Rick Steve bags - I like and use his smaller bags (civita and Appenzell) and I use one of his rolling suitcases. I don’t think I would buy his carry-on backpack compared to other bags on the market.
Osprey makes backpacking gear and uses this know how in their travel bags.

I'll second the recommendation for Ecohub bags. I bought mine on Amazon in July 2024 and have taken it on two trips to Europe and numerous trips within the United States. It has held us very well and is very comfortable, as long as you don't overload it (but that seems to be the case with most backpacks in my opinion). I have an Osprey Porter 30L and I like the Ecohub far better.

The current sale at REI has some great deals on the backpacks mentioned in this post.
The Osprey Fairview 40L is $138
The REI Ruckpack 40L is $111 (but be careful, as the stated dimensions for this bag exceed US carryon 22x14x9)
The smaller Ruckpack 30L is $76 (I have this bag with the plus-size shoulder straps, used it for a 6-day trip to Maui)
A couple of good-looking bags from Sherpani around the $140-$150 price point.

My husband and I used the Rick Steves Travel backpacks (convertible carryon version) for a few years. We travel carryon only, and that is our main bag which is put in the overhead bin on airplanes. I didn’t think it was particularly comfortable to carry, but the size was good for me.
We both upgraded to new backpacks this year. I got the Osprey Fairview and he got the Cotopaxi Alpa. We are both really happy with the new bags. They are 100% more comfortable than the RS Bags, and they pack better too. To decide, we visited our local REI Store and tried on several models with the weights that REI provides. The return policy of REI also gives confidence.

Whatever you’re considering, be sure to check it out with the amount of weight you’re planning to carry. Personally, I love the features of my Cotopaxi 35L (easy to pack & retrieve items) and use it on a lot of trips. But, I wouldn’t like it if I was trying to carry 20 pounds in it. (Mine is packed at 13 pounds.) It has a nice hip/waist belt.

Here I go again.
Osprey.com
Daylite 35 liter Travel Pack. = $120.
There is, also, a smaller 26 liter version for $100.
My only “issue” is I wish there were other colors. But, basic black and blue exists with one weird color combination called something like alkaline.
This travel pack checks a lot of boxes for ease of use, simplicity, lightweight, durable, cost effective, and I assume (never have used) comfort.
Note: I do use a different Osprey pack and the comfort and function is there.