Is Cash Flow really King?

[Christopher Leong E]

I'm looking to buy my first investment property. 

I found some rentals in Alberta and Sask., but the appreciation in these markets are close to zero.

Provided they are cash flowing, are places like this still favourable? I am assuming 0% appreciation. I understand there is forced appreciation as the my mortgage is being paid down, but is that good enough?

Should I avoid places where appreciation is flat or close to zero? or if the cash flow is positive, that should be good enough?

My goal is to expand my portfolio and increase our wealth as a family. I want to get an investment property because I like the idea of leverage and I guess in 25 years i'll have a small cash cow or I can sell the entire property for a lump sum and use that to help fund my retirement/other plans.