DOWN PANTS OR THICK BASELAYER BOTTOMS?

"Wondering whats best for winter leg protection,pants or baselayer like R1 bottoms?And synthetic or down and what brands?thanks"

I think it depends on whether you are on the move or sitting around camp.

R1 and other heavier base layers will very likely prove too warm if you are exercising strenuously. My own personal preference for hiking is Under Armour Cold Gear Base 1 or Base 2 under a wind pant, in my case MH Transition Featherweight Pants(no longer made). There are many other equivalents out there, but the idea is break the wind and transport your sweat outward. Around camp is where you will want more insulation, again with a wind barrier. Lots of options

I have a pair of fleece pants for around camp whilst winter camping in the sierras. Slip them on over my softshells (which are over a pair of cap 1 tights) and I"m good to go. Bulky and heavy but cheap and dual purpose, since I'll wear them more around the house than the 3 or 4 nights I might snow camp a year.

How cold do your winter trips get? The most I want when moving is a silkweight bottom (e.g. silk or cap1) under a softshell pant.

For me a big concern is ease of use; a pair of insulated pants I can pull on in camp seems much easier than having to first remove my pants to add or subtract an underlayer. I also find even the R1 bottoms are not enough when standing still. I don't currently have a pair, but I'm keeping an eye out for some relatively inexpensive puffy pants with full side zips.

for snowshoeing in california I use a cap2 baselayer with regular hiking pants and thats always been fine.But i was thinking of doing overnight snow camping.Also just to have something warmer than my setup in case of emergency.
I really have no idea about a pant system for real cold temps.

Goosefeet down pants are awesome for hanging around camp. I like to keep them protected by wearing them under some shell pants around camp. They're virtually always much too warm for wearing on the go. I normally carry regular thickness tights/baselayer for the legs, downpants and shell pants for my legs.