I have struggled with trench coats. I love them in theory, I love the military vibe of them, and have tried a couple over the years (thanks to those darn "must-have" lists!!) Turns out, I am just VERY particular about my trench, and finally have one I love.
Where I live, winter is long, cold, snowy. Summer is about 3 months of humid heat. Shoulder seasons are brief.
Here is what I've boiled it down to (for ME):
1. Weight or insulation of the jacket doesn't really matter. I am fine layering under it, sometimes with a down vest for extra warmth.
2. I LOVE a topper like a trench if I am running in/out of buildings a lot during the day, since the temperature inside is usually the polar opposite as the weather outside (I sweat in the grocery store in the winter!)
3. Traditional beige ones look terrible on me unless I am wearing color near my face.
4. Shape, style, and length are key. I find that I look better in a trench that has a substantial collar, non-shiny buttons, and knee-length or longer. Interior pockets are always a plus.
5. It turns out that although I am drawn to a very military vibe, I don't like how I feel wearing it. I do prefer to wear a much simpler style.
6. I like to switch out the belt sometimes, or wear it open like a duster, with the belt tied in the back.
Maybe it's just a matter of doing a deep dive into the particulars of what you like? If you have secondhand options near you, it's a great way to test out different styles to find one that works for you.