Hi there,
Both CNR and CP are foundational stocks. At the time, we chose CNR because it provided better value, at similar growth rates, a higher yield and had a more reliable history of dividend growth. Much like Canada's banks - each will have their periods of outperformance and underperformance against each other. But both are solid long-term investments.
A number of years ago, CP had operational issues which led to the suspension of dividend growth for period of about three years which also meant, it lost its status as a reliable dividend growth stock. CNR has been more consistent, and its 25-year dividend growth streak tied for the 10th longest streak in the country. Over the past five years, it has growth the dividend by an average annual rate of ~16.5%. Of note, CP will regain its Aristocrat status next year as it will exit 2020 with a streak of five-years. It has raised dividends by an average of ~17.5% over that time.
Overall however, both make solid foundational stocks.
Mat