There are many roofing companies in Vancouver with most fitting into one of three categories. The first category is the regular roofing crew. They generally go from one job to the next not giving a warranty at a really low cost. The risk of course is that you are at the mercy of the roofers ability to do the job right. If they don't and they gave you a manufacturers warranty, the warranty doesn't mean much. It doesn't cover not following the specs so you may end up paying more than everyone else when you get a another new roof shortly after and not for the cheapest price you can find
The second group is your local registered roofing company have been in business in the greater Vancouver region for over 10 years. It takes about ten years to get rid of the bad eggs, plus a company that last longer than ten years has dealt with warranties issues and that is a reality of any roofing company. They average with price but beware there are some companies that pose as group three's but are offering a regular line of product. Most deal with shingle roofing and are handing out a 30 year warranty
The third group is the high end roofing companies that generally deal with products that are unusual or difficult to install. You pay for what you get, there are some pretty strong and impressive products out there. They tend to sell metal, slate, cedar and rubber roofing
Always get three estimates so you can compare apples with apples and get a idea of the types of Vancouver roofing company you are getting. If you ask for the same product from each contractor that comes by your home you can also take a look at whether anyone is taking short cuts