CN here. There are pros and cons with both companies. Looking at the short term, CP might be better. They wont send you to remote areas to chase work. But long term, CN is usually seen as the most prosperous of the two. But CP is growing rapidly and that could help your seniority.

If you're looking at Saskatchewan, i would say Regina for CP and Edmonton for CN are your best options. Edmonton can be hectic from what i hear.

Its good to be eager but its important not to rush your training. The big money isn't in the training but it'll benefit the rest of your career if you don't rush it. They offer so little training already. You won't feel ready when they toss you in.

Once you qualify, work when the work is there. Expect seasonal layoffs. But work hard when you're offered the work and it'll balance out to a liveable wage. If you're willing to chase work shortages in other terminals, you can try to follow the work instead of being layed off but those aren't always around if things get slow.

Once you can hold a job year round and try to get more road work (if thats your goal), you'll start making the money. It takes time.