Fellow black dude here. I've recently spent time in all the cities you listed, and I would say go with Copenhagen or Stockholm. Helsinki and Oslo are more like big towns, you'd easily get bored in those two. Oslo has plenty of nature, but not much else. Not to mention the cost of living there is insane, you will quickly go broke without a high paying job. Helsinki is like a cheaper Oslo without the nature. Cph and Stockholm are proper cities with a good amount of stuff to keep you occupied.
As far as women, you will do well in any of those cities. Only speaking as a black guy, but I've had zero trouble getting consistent dates, ONS, and everything in-between in all of those spots. If you're decent looking, in good shape , and dress well, pulling wont be an issue at all. I noticed it was a bit easier to get ONS in Helsinki and Oslo, as they're somewhat like Iceland with little to no stigma around ONS. If a girl is interested in you, she will usually be open to going home that night. At least thats been my experience (I literally had two girls arguing over who would take me home one night in Helsinki). As like anywhere else, 9's and 10's will be more work, but definitely not out of the question. In any case, there will be a steady stream of 5-8's giving you plenty of attention. Looks wise, those cities are all pretty similar with the exception of Helsinki, I saw noticeably less quality during my time there. If i had to rank by the quality, I would say Oslo, Copenhagen, Stockholm, all pretty close in that order, Helsinki a distant fourth.
Just wanted to share some quick thoughts. Hope this helps any.
As far as women, you will do well in any of those cities. Only speaking as a black guy, but I've had zero trouble getting consistent dates, ONS, and everything in-between in all of those spots. If you're decent looking, in good shape , and dress well, pulling wont be an issue at all. I noticed it was a bit easier to get ONS in Helsinki and Oslo, as they're somewhat like Iceland with little to no stigma around ONS. If a girl is interested in you, she will usually be open to going home that night. At least thats been my experience (I literally had two girls arguing over who would take me home one night in Helsinki). As like anywhere else, 9's and 10's will be more work, but definitely not out of the question. In any case, there will be a steady stream of 5-8's giving you plenty of attention. Looks wise, those cities are all pretty similar with the exception of Helsinki, I saw noticeably less quality during my time there. If i had to rank by the quality, I would say Oslo, Copenhagen, Stockholm, all pretty close in that order, Helsinki a distant fourth.
Just wanted to share some quick thoughts. Hope this helps any.