Both north and south Vancouver Island have resident killer whales that you can see all year. Between April and October you can also spot other kinds of whales, especially gray whales and humpback whales. South Vancouver Island (Victoria) is a popular place to take whale watching tours since it is easy to get to. But they have less resident whales and are further away from the areas where gray whales and humpback whales normally travel. Northern Vancouver Island has more resident whales and it’s easier to spot humpbacks there. You have a good chance of seeing whales from either location though, but if the question is which is “best”, I’d say northern Vancouver Island.