You all know that, prior to purchasing the MBP I now own, I was using a M1-era Macbook Air 13".
I'd been carrying that in a small tote that I got from work - swag from McAfee. It was a small laptop/tablet bag that was surprisingly adequate for a 13" MBA. I used it a long time and used it to fly out to California and New Orleans. It'll fit under a seat on a plane and still leave room for your feet.
I'd not planned on getting a MBP when I was in California. I could've waited until I got back but it was a snap decision and once I saw that an MBP was locally available while I was in CA, I was stubborn.
I bought the MBP and then realized that a 14" laptop wasn't going to fit in my current bag (plus, I still had my MBA with me), so I had to buy a new bag just to get it home.
What did I buy? I bought the Modern Utility Laptop Backpack for 15.6" Laptop, which is made by Samsonite. It's charcoal in color. It fit most of the existing gear I had brought with me, as well as the new gear - MBP and accessories; Airpods Max and accessories; 11" iPad. I couldn't believe that it held all of my electronics and didn't feel heavy.
There are two pockets designed for flat electronics (tablets and notebooks). Those pockets were lined with cushioning for protection of the electronics.
I like this setup better, not only because it will fit a 14" MBP, but because it's a non-bulky backpack.
It has a TON of pockets. I tried to stash like things in every pocket and ran out of things before I ran out of pockets.
The straps are comfortable - I did a lot of walking/toting.
I really like this bag!
I'll still use the little side pack for my MBA but I might not use the MBA all that much. I may do a factory reset on that one and sell it, although I'll ask the wife if she wants it first.