Through minor midget, there's really no difference between the US and Canada. The two systems are comparable and US teams are competitive against Canadian teams.
The difference comes in the 16 and 17 year old seasons (a player's NHL draft year and the year before) - the CHL seems to be slightly better at developing players when they are 16 and 17 years old than the USHL is. The obvious exception is the NTDP, which is clearly the best option for anyone eligible to play for them.
When a player hits 18 and enters college (some later bloomers enter college when they're older, and they obviously aren't relevant to our conversation), the NCAA is probably the better option. Players mature and develop at a faster rate in the NCAA because of the added practice time and the fact that they are required to manage their time, live on their own, etc.
When a CHL player goes undrafted, a lot of times that player is seen as having no future in hockey and CHL teams will often begin developing and utilizing that player in a role geared more to serve that CHL team's ends than to develop a professional prospect. By an undrafted player's 19 year old season, the CHL team is basically trying to develop the best overager they can, in hopes that the player will return and help them win.
If you're one of the top guys and have a legitimate chance at going in the first round of the NHL Draft, I'd say you're probably better off going the CHL route (unless, obviously, you're an American and have an NTDP invite). If you're not such a sure thing to get drafted in the top two rounds of the NHL Draft, you're much better off going the NCAA route.
Ideally, the CHL would become a U18 league, so CHL players would retain NCAA eligibility and CHL players would truly get the best of both worlds. But there's no reason for the CHL to make that change, and the NCAA would be foolish to allow CHLers to play the way the CHL is currently structured.