Canada, eh.

I use this one: https://store.ricksteves.com/shop/p/classic-backpack

Unless you really overstuff the thing, you can fit it under the seat in front of you on the airplane.

It's from Rick Steves's store. He started business as a tour guide in the mid-1970s when he was about age twenty. Since then he's done a good business writing books, giving tours, et cetera. He usually has some kind of travel series going on PBS.

Bring along a smaller pack for day to day tourism, something like this:

https://store.ricksteves.com/shop/p/packable-backpack

The advantage of doing it this way is the ease of travel. While everyone else is waiting for their checked baggage, you just walk off the plane. You're the first person to go through customs, and with only the backpack to search, that's a snap.

The disadvantages are these. First, you can't bring much. I travel during the summer, so I can use thin, lightweight pants. If you put three pairs of blue jeans in that thing, plus a toilet kit and other clothes, you've pretty much filled the thing to capacity. So you'll be doing laundry every few days.

Also, if you're young and healthy, carrying that backpack won't be a problem; but if you're older it can get to you. If you have any doubts, try packing the bag then walking around town with it, window shopping, for a couple of hours. You might find yourself better off using a more conventional bag with wheels on it.

Steves advocated that style of travel for a long time. He started as a "see Europe on $10 per day" kind of guide. Later he got married and had children. He immediately acknowledged that when you've got kids along, doing it with just one bag per adult is impossible. So there's that to consider.

Finally, there's security. With all your possessions in one bag, if it's lost or stolen you've got a problem. Naturally you should keep your passport, credit cards, and other vital stuff elsewhere. Steves recommends a money belt, something like this, worn around the waist under your shirt:

https://store.ricksteves.com/shop/p/moneybelt

I disagree. His merchandise is good quality, but the claim that the moisture-barrier liner will protect the contents is bogus. I tried one of these for my first trip, and everything in it got soaked with sweat. Not a problem for a passport and credit cards, but that can do a number on an airline ticket or rail pass.

I use this instead:

https://store.ricksteves.com/shop/p/hidden-pocket

Run your belt through the loops. He recommends then stuffing the pouch inside your pants, but I found that was unnecessary. I just let it hang down into my pocket. With something the size and stiffness of a pasport in it, it's kind of difficult to get out of the pocket, so I don't think a pickpocket could successfully get at it without my noticing it.

And, if you bring a laptop or some other electronic gear, you'll need some like this or the equivalent for wherever you're headed to:

https://store.ricksteves.com/shop/p/uk-power-adapter

That's only a plug adapter, not a voltage converter. Most electronic stuff can take 100-240 V @ 50 or 60 Hz, which pretty much covers you anywhere. A lot of other electric things don't take that range though. When I went to the UK I could use one of these and plug my laptop in, but my electric razor wouldn't have worked.