Diversify. It's very well possible Canadian ones getting the head start on the rest of the world become big established multi national companies and if US takes years to be federally legal. Who's to say the big ones won't just come in from Canada and make it hard for small American ones to compete.
On the other hand as you said US market is going to be lower price and untapped opportunity in a country that at the end of the day is a much bigger market. So get in early you do good.
But it's also might maximize your gains by making it big on Canadian market cashing out and then catching the next wave of the greenrush on American weed stocks.
We can't predict the future though so diversification helps, it may pay off well. My self I'm more interested in companies looking to do US and Canada business there's a couple of these. They can't bring weed across the boarder but instead grow in US with American subsidiary and grow in Canada (or intend to). This way should recreational become federally legal in the US they already have establishes branding and business in both companies, then trade routes just open up for them.