The short answer is that what’s “better” is what works for you in your situation. As a general rule, though, converting AmEx points to Frequent Flyer points and using those points to book reward flights will give you the best value for money. However, finding reward flights to anywhere in North America is not at all easy, so I wouldn’t be picky.
My suggestion is that you look for reward flights on any airline you can, and if you find them, grab them. You have the luxury of being able to use your AmEx points on almost any airline. If you find reward seats on a Qantas or Oneworld flight, convert your points to Qantas (Ascent Premium only) or (possibly even better) Asia Miles. If you find seats on Virgin or Delta, convert them to Velocity points. Or for a Star Alliance airline (eg Air NZ or United), convert them to KrisFlyer Miles. Whatever you find, if it’s convenient and works for you and available on the dates you want, grab them while you can and convert the points accordingly.
I would then use the AmEx travel credit for something else – accommodation in Vancouver, perhaps?
However, if you can’t find reward seats for when you want to travel, then you might decide to use your points for cheaper flights via AmEx Travel. If it works for you, it’s worth doing.
The one weakness in what I’ve suggested above: during the time it takes to transfer the points from AmEx to the airline FF programme, you might lose the reward seats. So the less risky, simpler, easier, less stressful – but not-as-good-value-for-money – option is simply to go through AmEx travel to begin with. Your call.
All the best as you plan your travel!