One can not emphasize too much the importance of proper clothing when hiking. If it feels too hot or too cold, it means that the clothing is not correct. With proper clothing even -30 deg is not too bad.
Nowadays I use very often Fjällräven clothing; both trousers and jackets. Not because of the trademark but because those seems to fit me well. But I also have some other marks also, like Didriksons.
My underwear is very often made of merino. It is soft as wool is, but it is not itchy. And what is the most important, it lets the moisture through it from your skin. Which means that it is not that wet as cotton is when you are sweating.
Also my socks are of merino. One nice thing when hiking is that they will not smell bad immediately like cotton or synthetic materials.
Merino cloths should not be washed as often as other materials. And also the material will not sustain as well in use as other materials. But they are rally comfortable, and that is important.
My shoes are not hiking shoes. Actually they are some leather safety shoes by Jalas. Also here the main reason is that they feels good even after a long walk. Because they are made of leather, I need to put grease to them a couple of times in a year. But that makes those to be waterproof also.