I own a denim shirt, white shirt, denim jacket, and trench, but it took a long time to find ones that worked and even now, they don’t get the wear they deserve.
Denim shirts—I rarely see people wearing them in real life. None of my female friends, acquaintances, or family members where them, and I don’t see them on the street, either. Why? I’m not sure.
Denim jackets—stiff and not ideal wear for those who experience real winter. They’re too bulky under coats, inadequate for rain when you want more coverage, and too warm for humid summers. I like mine, but it doesn’t get the wear it deserves for those reasons. When would you able to wear them regularly in Winnipeg? What about a denim-look blazer instead, or do you have too many blazers at the moment?
White shirts—you say you’ve tried them all. Guessing that includes different fabrications, oversized vs slim cut, but what about 3/4 sleeves and short sleeves to avoid the cuff issue? Now that I own a few, I don’t see them as essential outside of a professional work environment, though they get more wear in summer time.
Trenches—keep trying if you want one! Of all the items you mentioned, I would save up for this one, because of how easily it pulls an outfit together. When a trench fits and flatters, it has more of a “wow” factor than the other items. Maybe make a separate thread detailing what hasn’t worked for you, so the hivemind can offer suggestions?