Buy a bycicle - total noob?
You're not a total noob, you have ridden the first bike and know what you like and don't like about it.

I'm unfamiliar with the weather in Finland, but I guess winter means snow.  How deep a snow would you ride through before its too much ?

Your budget will determine whether new or used - anything new with a price tag under ~$500-600 USD will be a BSO, and while that might be okay, they're not built for lots of riding.

If your budget was $500, I'd spend $100-$250 on a nice tidy used bike, and use the rest for lights, helmet, vest, etc.  Save any leftover for repairs.

If your budget was $1000 I'd go for a new commuter bike (a rigid MTB with no suspension) with bigger wide tyres for $600-$900.  If snow and ice is a significant part of winter, then consider spending some of the difference on some studded snow tyres, and keep your smoother commuter road tyres for summer.  Also, you'll need a helmet vest and lights.  

A Yowie is also good for cold weather riding, as are gloves and overshoes.  You may have some of this already.