
I go back and forth with Sitka/Kuiu and find myself using a handful of both sets of gear. I wore the Timberlines and the Attacks 1st rifle season in CO this year. Temps (per my Garmin) mid 20 to mid teens at night and highs @40-45. I'm 6', 185 lbs, lean, with a fast metabolism and get cold fast. I was in the same boat earlier this year so I took both to end the confusion! I took the Attacks and the Timberlines. Both were great pants but big differences for me.
The Timberlines were warm and did a good job with wind, I sit on a pad when glassing (and typically throw on my rain pants so that I don't get cold) so I didn't "test" the seat being waterproof. I like the taper of the leg of the pant for gaitors, and the belt loops are beefy. These fit me really snug in the seat/hips and crotch but perfect everywhere else with the right pant rise too.

The Attacks were just easy, and wore like a pair of sweatpants. I absolutely loved the hip vents, non-zip front pockets, and they were more comfortable on horseback during the ride in to camp(9miles). I also noticed more stretch in the Attacks, which I really like. This could be because of the waterproof patches in the Timberlines (waterproof seat/knee). The belt loops aren't nearly as beefy and I could see them being an issue long term. No knee pads but thats never bothered me, if necessary I use my glass pad for my knee (cleaning meat).
Both dried quickly and DWR coated, and neither took on much odor either. Warmth wise they were very very similar to me with Sitka core light weight bottoms and SmartWool NTS 150 boxer briefs.
I'd also check out the Kuiu Talus pants. My Dad wore his for 6 days straight on this trip and they did great in these temps. He wore light weight base layers under them the entire time. He got hot one day on a lengthy hike, hip vents put a huge smile on his face. He said they blocked the wind really well also. He didn't wear his rain gear glassing, he didn't need the warmth.
I really don't think you could go wrong with either, both companies make great gear. I'll waffle back and forth but I really think Sitka needs to update the Timberlines (again) or add another pant to the big game line. Something that fits like the Apex (which I really like) with more warmth. I also wish they'd both start putting clips on the front of cuffs to hook to your boot and keep them down. Less logos would be nice too. If your backpacking I'd go with the lighter Attacks with heavy base layer. I like the guides but I'd buy the Talus if I wanted more warmth and roll with a heavier base layer (it'd be a lighter setup likely).