After having spent a lot of my working life trotting around the globe
with conventional luggage, I tried using backpacks after retirement and
became an instant convert.

My favorite backpack has a large central compartment which zips open
around the entire front of the backpack for easy loading, and has an
accordian-style expansion section on the bottom which can be secured in
the closed position by a wraparound accordian zipper (one hopes that
description is understandable). Besides the large main compartment,
there is also a toiletries compartseveral and five separate smaller
zip-close compartments of various sizes. I bought this in a
street-front luggage store while passing through Hollywood CA for just
$30, and wish now that I had bought several.

I have on occasion (usually returning from trips wherein I overshopped)
had it loaded with over 50kg of miscellaney. On those occasions I
cinched up the hip-hugger part of the carry straps, and had little
trouble carrying it once I was up, balanced, and taking the weight
primarily on my hips and legs. I am 60+ years of age, and could never
manage that much weight with conventional luggage outside of a
smoothly-paved airport envirionment with luggage carts available.

I normally travel on short trips with the expansion section of the big
bag closed and the bag very lightly loaded. Packed this way, it can be
carry-on luggage. Sometimes on short trips I pack a smaller backpack
inside of the big one, and use the smaller one while shopping around
town or in other situations where I need to carry a small amount of
gear locally. If both the big bag and a supplemental smaller one end up
fully packed, I find that it is possible to carry both by putting the
smaller one on backwards as a front-pack.

The big backpack has attachment rings on the front of the shoulder
straps and I have attached carabiners to those rings. I occasionally
carry some items (e.g., a laptop & case) hanging in front from those
carabiners.

I also tend to carry a big multi-compartment fanny-pack; usully
positioned as a belly-bag or on one hip. I use that to carry items
which I might need while traveling (e.g., toiletries, paperback books,
travel docs & tickets, etc. etc.) but which would not fit conveniently
into my pockets.