>3-in-1s look interesting

They are tempting, but not really that great. There's no need for your layers to zip together, it's just more hassle to give yourself less flexibility. Just put on an insulating layer when you need it, then add a shell over it when you need it.

That said, the convertible ones can be a good deal if you look at it as buying two separate jackets if you need both anyway.

But to answer your question, I have a Columbia puffy jacket that works for 90% of everything, then I'll just adjust my under layers as necessary. This time of year it's just like a tee shirt under the jacket. In a few months, it will be more like a sweater or fleece under the jacket. It's also light and very packable which is nice.

Brand doesn't really matter, but for reference mine is like this (that I got at the Columbia outlet for like $30): https://www.columbia.com/p/mens-powder-lite-insulated-jacket-1698001.html