The reason why the rucksacks that I recommended above are in my opinion the best choice, is apart from price, durability and fit that one can organise the equipment very well in them, for example this affordable choice here:
Rucksack Dutch army Sting, used
Sleeping bag
British army light and medium weight sleeping bag with liner, new.
(Of course you just take with you what's needed in the season.)
Bivvy bag, British army, MTP, new
(Sleeping bag in bivvy bag stuffed to the bottom of the rucksack.)
Army closed cell foam roll mat, British, used is OK. (Outside under the flap)
Military poncho, used German army, or British army shelter sheet MTP or better DPM in good condition, (right side pouch)
Cordage
2x 3 metres to tension it as lean to shelter, and 1,50 metre to make a tripod.
If you don't have cordage, don't take the everywhere recommended Paracord, unless you get the real one used and cheap, for Example from Endicotts.
The better choice is Edelrid Multicord SP 2,5 mm orange. It's far better and especially far lighter!
Fleece jacket Solognac Fleece Recycled 500 or similar
in a dry bag (7 litres Ortlieb PS10) as pillow too, together with
Spare underwear 1X
Briefs and T-shirt, cotton.
Woolen spare socks 1X
Swimming briefs 1X
(That goes on top of the sleeping bag in the main compartment)
Toilet paper in a zipp lock freezer bag
(Top pocket)
Wash kit
Folding tooth brush, tooth cream, biodegradable soap in a small bottle (Sea to summit body wash is refillable! Large bottles from the organic food shop) and disposable razor (Wilkinson's orange don't break) wrapped into a small microfleece towel (Nabaji size S black) and stored in a zipp lock freezer bag. Plastic signal mirror for shaving.
(In utility pouch)
Food
in the
Mess Kit used from the Austrian army
(Left side pouch together with knife and spoon. The mess kit in a plastic bag!!!)
Field bottle, 2x ,British army original Osprey 58 pattern, available in Britain new and cheap.
BCB Crusader mug, stainless steel, uncoloured. New or used doesn't matter.
(Plastic bag around the mug!)
British army MTP bottle carrier pouch 2x used, Fits into the loops on the belly of the rucksack.
British army MTP utility pouch 3x , used, for wash kit and other small stuff, also mounted on the belly of the rucksack
(You have a place for everything and always everything in its place, easily accessible.)
British army folding stove, used.
Spoon stainless steel from the flea market
Candle In a zipp lock freezer bag, a few drips of wax can be used as a fire starter
Bic cigarette lighter, orange
Head lamp Petzl e+lite
ON THE MAN:
Hiking boots Schladminger 100
Woolen Socks British army arctic, new
Underwear
Trousers or shorts, polyester-cotton blend, Solognac Steppe 300 and Shorts 100 are cheap and good. Austrian army too.
Handkerchief , cotton
Several times folded usable as pot holder and pre filter before water purification by boiling. New or used military surplus, because olive.
Purse
House keys
Bic lighter, red
Belt Solognac 100 or similar
Knife, Morakniv Garberg stainless steel with leather sheath
T-shirt
Shirt
Buttoned long sleeved shirt with two pockets and flaps over it. For example Austrian army, heavy version KAZ 75 used.
Compass Suunto M-9 or whatever you have
Topographical map
1:50 000
One can take of course different stuff, the selection above is durable and currently available cheap and it fits well into the rucksack like this, what's the most practical way to organise a rucksack.
You should of course first look into your wardrobe case, attic and shed if you can find similar stuff there. But if you need to buy new equipment have a look at that too! That's what I would buy now would I have lost all my stuff and just a limited budget.
But I manly wrote that down here to explain the principle. And like that you can't put your equipment in most other rucksacks. There are a lot of others that are similar but they are mostly much more expensive.