The landscape has changed since I came in 2018 (after some parliamentary rumblings, the big telcos rolled out "unlimited plans"), but for context, a 5gb plan was considered a large data plan, and generally was in the $80+ range when I arrived, starter plans were generally 2gb in the $60 region. Extra data wasn't throttled, it was charged for at a high rate.
The plan I was referring to is an older tmobile plan with 3 lines on it. They come out to just under $50 cad per line including taxes/fees and that includes 5gb of Canadian/Mexican LTE/5g, unlimited 3g after that, as well as unlimited everything in the US, and no extra charge to call anywhere in NA.
I can roam on Bell, Telus or Rogers, so tend to get better coverage than my Canadian friends. I also get unlimited worldwide texting and 2g data when I travel for no additional charge.
If I switched to one of the new t-mobile plans, I would be paying $59/line, but that includes a free Netflix subscription, and 10gb of Canadian data.
I just priced out a roughly comparable rogers plan for the features I actually use (5gb, unlimited US calls, data in the US) and it comes to $65 CAD + $12 per day I'm in the US, or go for the unlimited US plan which is $105 CAD on a promotional offer right now. Add on another 12% for tax and a bunch of fees I'm sure I'd learn about after the fact, and keeping my US service is very competitive. Rogers new plans, are pretty new (I believe unlimited data only started in 2019 or 2020, and their definition of unlimited is 20gb).
The takeaway for me is that if I was just a single line, and I didn't leave Canada much, I would probably pay slightly less. Since I call and text the US daily, and travel there for at least a month a year, I save several hundred dollars a year on tmobile, and don't have to worry about getting billed hundreds or thousands because I forgot to buy a data pass for a trip across the border.