When I did lots of travelling, about 20 years ago, I had the absolute perfect rucksack.
It was
*about 50-60l
*zipped open like a suitcase, not stuffed from the top, with extra pockets at top, bottom and sides
*had a cover in a pocket at the bottom that zipped over the straps to make it easier to get in and out of bus and aeroplane holds
it also had a waterproof cover, but they may have something I bought separately.
I've looked at a few places online but can't see anything that quite fits the bill.
Can anyone help me find something similar now please?