I’m a big fan of side-zip pants / easy on and off (for any layer). Weather changes a lot, and fast in the coastal regions of Norway, so being able to adapt quickly, without too much hassle is appreciated.
This thread went a little all over the place, so I’m not quite sure what you’re after, but I like that. More fuel for my imagination:)
The garments I use that best match your description is two 3/4 length zip longs from Northern playground (Norwegian brand). One is merino wool and the other is a smooth faced fleece. I’ve actually used the fleece more, but both are great.
A new addition this year is the Outdoor Vitals dragonwool zip longs. I ordered the full length version, but it’s not quite full length IMO, more like 7/8. Although a bit misleading, I find this preferable to a full length as it doesn’t overlap (as much) with my socks and doesn’t get wet quite as easily. Haven’t used it enough to endorse it quite yet, but it does add versatility to my wardrobe.
It should be said; zip off pants makes adjusting layers a lot easier, especially with skies on, but it’s still something you don’t want to do too often. In high winds or with cold hands it can take a few tries before everything is aligned and zipped.
I’ve recently started looking for 3/4 insulated pants with side zips. Preferably down. Initially I was searching for full length pants, but realized it’s not really necessary. The problem with 3/4 insulated pants is that there is less to choose from and a significant portion seem to be a bit too short. I guess I technically want slightly more than 3/4, but some offerings are only shorts/knee length, and I really don’t see a need for that. Maybe not quite what the OP wants, but would be interesting to see some recommendations if it’s considered within topic.