I apologize for bumping this old topic, but I have done quite a bit of research on this, so I want to share my experience.
I thought I'd throw a few more cents into the discussion.
or most conditions (lighter precip days in winter, early spring conditions) I wear a pair of Patagonia Backcountry Guide softshell pants They're very comfortable, loose enough to allow layering, and they vent well.
When it's dumping and/or I am going to be skiing in deeper conditions, I wear a pair of Flylow Chemical pants. They are bombproof pants. The venting is versatile with inner and outer thigh vents. The knees are reinforced and articulated and the waist is adjustable to accomodate layers. The fit is a little looser than I like, but the protection and comfort are undeniably good. (I got both of these in nearly-new used condition off of the TGR gear swap for about half of retail.)
In late spring and early summer, I go with a lighter softshell pant made by Mountain Hardwear. (I think the model is the Chockstone.)
In t-shirt conditions, I wear a pair of Kuhl Liberator convertible pants.
For splitboarding, I have a pair of Patagonia Backcountry Guide soft shell pants https://pro-sport-expert.com/best-ski-bibs/
I really like them; they've got an internal gaiter that fits over my boots and venting for when I need a bit of cooling. They've been durable. They are, however, expensive if you buy them full retail (I got mine on clearance.) For spring adventures, I might wear my lighter soft shell pants (the PG Alpine Guide) and I've used regular hiking pants for summer and fall snowboarding (the kind with zippers on the legs so I can get them to fit over my boots.)
I couldn't imagine touring in a pair of hardshell or insulated pants (hot!). I've never needed super waterproof pants when splitboarding; the softshells have been good enough.