Sweden. One trip together with my parents when I was younger, I didn't enjoy that trip. I also had a trip later on, about 2 or 3 years ago, this trip was nice, my host was not particularly fond of the increase in criminal activity in the area, she felt unsafe, so that kind of made an impression.
Denmark, had a few trips to Denmark, again when I was a child. I can't recall all of them, they've all been nice as far as I can remember. A year back or so I had a one-day trip to Denmark with 3 of my friends, we went to an amusement park, we had a nice time.
Germany, a few trips there visiting my ex, a couple of years back or so, had a nice time. The town was not too far away from Essen, it looked quite old, kinda reminded me of movies from the 70s or so. I also had a trip to Germany when I was in middle school, it was through Denmark, then Berlin, and towards Poland, the impression which really stuck at that time was how much better everything was in Germany compared to Poland (Doesn't beat my country though, hah).
Poland, a shithole country. Visited it once, dirty lavatories, gypsies getting chased around my the police, nasty food (to be fair, the quality of the restaurant was quite bad, but come on... worms in the salad, and only the outside of the chicken wing being cooked, ffs, I don't want to eat blueish chicken and hard macaroni...), honestly I went hungry a good amount of the time, because I really didn't like the food, the McDonalds felt like a rescue.