I've skied at Sunshine and Lake Louise, and I'd say on the plus side: from a terrain perspective both are true big mountain experiences, with 3,000+ ft. vertical, big open bowls above treeline, and lots to explore with good options for any level skier. Lift lines by most American resort standards would typically be minimal. So you can get a lot of skiing done in not much time. The scenery is spectacular, especially at Sunshine. It is definitely one of the most beautiful places I've ever skied, but a lot can depend on the weather.
Which leads to the cons: The Canadian Rockies can be cold, so much like places in the U.S. such as Jackson or Big Sky, you might find some days between December and February where highs are around or below zero, but at least cold usually means it will be clear. Because there are so many other ranges in B.C. that storms cross before they reach the Rockies, they do get less snow, though the cold often means the snow stays dry. Banff or Lake Louise are pretty much the only options for places to stay. Banff has a lot going on for shopping, dining, and other activities, but you are 20 minutes away from Sunshine and about 45 from Louise. So shuttling to ski whether by rental car or hotel van is a daily add on. Actually I just noticed that there is a lodge up on the mountain at Sunshine that is the only ski in/out at either area, but you'd have to be OK with having nowhere else to go after hours.
You can stay in Lake Louise and be close to the hill there, but then there are limited options for dining or nightlife. If you want to splurge, staying at either of the old C.P. hotels (now run by Fairmont), the Banff Springs, or the Chateau Lake Louise are a classic experience with so many comforts you won't be too worried about going anywhere else.
Overall, I'd say go if you want to do the "whole" experience of taking in the scenery, and maybe checking out other activities around Banff like snowshoeing, ice climbing, or lake skating. Strictly from a good snow and skiing perspective, there are definitely places to go where the snow and weather are more reliable. Looks like it's can't miss in most of the West this year. I'm not sure what the conditions are like in the Rockies now, but B.C. is almost as good as it gets. Go to Fernie, Revy, or Red and book a cat trip as the cherry on top.