Tokmanni - Small, cheap, and all over the place
Clas Ohlson - Lots of their own brand products, okay quality and okay price
Prisma - Large store with lots of choices, but hard to get to from the city center
K Citymarket - Large store with lots of choices, but not too many locations.
Saiturinpörssi - Super cheap, but hard to navigate
Stockmann - The center of city life. It’s expensive, but if you’re looking to splurge it’s the place to go.
Kierrätyskeskus (yes, it’s as hard to pronounce as it is to spell!) has lots of cheap, secondhand furniture, silverware, etc.
Ikea - you know Ikea
Jysk - It’s like Ikea, but different
Maksu - It’s like Jysk, but different
Granit - Very Scandinavian aesthetic for a quite reasonable price
Tori.fi - a secondhand website, but only available in Finnish. Use Google Translate to help!
Facebook Marketplace - Has more search functions in English but fewer items for sale
Lidl - Cheap!
Alepa - Small, cheap, and all over the place
K-Market - a little fancier, a little less all over the place
S-Market - even fancier, but can be quite pricey
Herkku - if you need a specific food, the basement of Stockmann has an incredible grocery store.
Uff, Relove - Second hand stores have used winter clothes for very cheap, especially coats and outdoor gear
Tokmanni - cheap new clothes, but may not be high quality
Prisma - a wider selection of brands at a variety of prices
Outlet stores - Often they have good sales, but selection can be limited and difficult to get to without a car.
There are tons of brands for outdoor clothing in Finland and they are all generally high quality. Try not to buy from Zara or H&M as it might not be warm enough