I've used a few different climbing packs around that 40-50 litre capacity for both backpacking and ski touring. If the ski-touring is a significant usage then I'd ideally consider packs with a dedicated/external shovel and probe pocket - sure you can stash those things inside the main body of any pack of this capacity, but if you ever need to use them for real then you want them very quickly accessible. (And pockets like that can find uses for backpacking kit too.)
My current ski touring pack of choice is the Lowe Alpine Attack MX 42+10. I'm not sure if it's in the current range, but Lowe had certainly nailed a great set of well-thought-out winter features covering all the hardwear carry options, gloved usage, snow-shedding back panel etc. Even if that model's gone I expect a lot of those design elements live on. It'll carry a load well too, great low-profile hipbelt. Biggest downside is the slightly hefty weight, 1.7kg.
I've considered using my LA Zepton 50 for ski touring, but it lacks the shovel pocket and I reckon the mesh back panel could be a snow trap, but otherwise it'd work pretty well and it only weights about 1100g. I've carried over 15kg in it at times for backpacking.
Before that pair, I've used a POD Black Ice, and despite appearances the hipbelt and carry are very comfortable. On a 10 day backpack with all food at the start it lugged 23kg! I've also slung skis on it. giving a 20kg load, and walked several km. Tough as old boots too (it, not me
).
In contrast I tried one of the original Crux packs, a 45 litre one called the AK50 (which a year or so later Crux morphed pretty much unchanged into the AK47x). A great, simple pack in many ways but imo let down by the hipbelt - nice for a while with maybe 12kg in it but towards the end of a week my hips ached from trying to take the load on the belt and my shoulders had to do more of the work. I'm glad I never had to add my skis to the load!
Finally, on the trip I've just returned from, one very experienced guy was using an Osprey Variant 52, and was very happy with it. His only complaint was the zip on the inner lid pocket being in the wrong place so things could fall out when you opened it!