I have two small backpacks for day hikes. The Vaude is 24l and can be expanded to 28. The Essl is 30l.
The reason why I have two almost identically sized backpacks is that the Vaude shares its volume between multiple smaller compartments, and that turns out to be pretty problematic when you mainly want to stuff jackets and other large items in it. I only use it for family trips now.
The Essl has only one big compartment. features a zipper that lets me open the entire front, so I can get to any item, no matter in what order I packed it. I like that a lot.
My winter loadout is usually:
>Base layerTwo cheapo merino mix shirts, and just normal, good quality sports boxer briefs. On the feet I wear merino hiking socks. I'm still trying to find merino toe socks, but I can't find a pair that's thick and strong enough.
>Mid layerA Bergans Hareid hooded fleece jacket. I've had it for years, it's very robust and warm.
https://www.bergans.com/de/p/3027-hareid-fleece-jacket/21466 (I have the previous model)
>Shell layerA Bergans Ramberg shell jacket. No insulation, just for water and wind resistance.
https://sportfits.eu/products/bergans-ramberg-2l-ins-jacketI use hiking shorts long into late autumn and early winter. Only when I expect more snow do I switch to RevolutionRace Rambler outdoor pants. If it's cold, I wear running tights underneath.
>HeadA Polar Buff is always with me because it's so versatile, light and easy to pack. It can replace scarf, hat and balaclava. Sometimes I bring a water resisting boonie hat with me, usually I don't need to.
>ShoesHAIX Black Eagle 2.1 Athletic. They mainly make boots for emergency services and produce in Europe.
https://www.haix.de/haix-black-eagle-athletic-2.1-gtx-mid-black>HandsUp until this year I wore a pair of pretty old Mammut fleece gloves, but they went missing. I recently bought Spyder Bandit skiing gloves. Haven't tried them yet, but I bet they'll do fine.
https://www.spyder.com/products/bandit-gloves-black 
